Thread safety in rte_acl

Thread safety in rte_acl

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Hi, I have two questions : 1. Is it safe that multiple threads will run "rte_acl_classify" in parallel  (on the same ctx )? 2. Is it safe that one thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,

Re: Thread safety in rte_acl

[Ananyev, Konstantin]

> 
> Hi, I have two questions : 1. Is it safe that multiple threads will run "rte_acl_classify" in parallel  (on the same ctx )?

Yes.

> 2. Is it safe that one
> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,

Just add new rules is safe, but applying them (calling rte_acl_build()) is not.
Konstantin

=?gb18030?b?u9i4tKO6UkU6ICBUaHJlYWQgc2FmZXR5IGluIHJ0?= =?gb18030?q?e=5Facl?=

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>> 2. Is it safe that one
>> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,

>Just add new rules is safe, but applying them (calling rte_acl_build()) is not.


In my case, there are two process sharing hugepage memory£¨struct rte_acl_ctx£©,  one process call 'rte_acl_build' to add and apply rule, another process call  frequently 'rte_acl_classify' to match rule, does it need to add lock? if not, is there other method to implement this safely?


------------------ ԭʼÓʼþ ------------------
·¢¼þÈË: "Ananyev, Konstantin";<konstantin.ananyev@intel.com>;
·¢ËÍʱ¼ä: 2018Äê1ÔÂ8ÈÕ(ÐÇÆÚÒ») ÍíÉÏ7:42
ÊÕ¼þÈË: "ÕæÎÒ·ç²É"<1534057243@qq.com>;"dev"<dev@dpdk.org>;

Ö÷Ìâ: RE: [dpdk-dev] Thread safety in rte_acl



> 
> Hi, I have two questions : 1. Is it safe that multiple threads will run "rte_acl_classify" in parallel  (on the same ctx )?

Yes.

> 2. Is it safe that one
> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,

Just add new rules is safe, but applying them (calling rte_acl_build()) is not.
Konstantin

Re: 回复：RE: Thread safety in rte_acl

[Ananyev, Konstantin]

>> 2. Is it safe that one
>> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,

>Just add new rules is safe, but applying them (calling rte_acl_build()) is not.

> In my case, there are two process sharing hugepage memory（struct rte_acl_ctx）,  one process call 'rte_acl_build' to add and apply rule, another process call  frequently 'rte_acl_classify' to > match rule, does it need to add lock? if not, is there other method to implement this safely?

Yes, you'll need some sort of synchronization.
Lock (or rwlock) is one option, but as build could take quite long time - probably not the best one.
Another way - have a struct cthat ontains pointers to 2 ctx and an index for active one.
Then you can do classify() on active one while doing add_rules/build on second one.
Then when the second one is re-build you can switch an active index to it.
I think librte_table uses that method.
Of course you might need a reference counter or some other way to deternine that
no-one is using old copy anymore and it is free to update it again.
Konstantin 


------------------ 原始邮件 ------------------
发件人: "Ananyev, Konstantin";<konstantin.ananyev@intel.com>;
发送时间: 2018年1月8日(星期一) 晚上7:42
收件人: "真我风采"<1534057243@qq.com>;"dev"<dev@dpdk.org>;
主题: RE: [dpdk-dev] Thread safety in rte_acl

> 
> Hi, I have two questions : 1. Is it safe that multiple threads will run "rte_acl_classify" in parallel  (on the same ctx )?

Yes.

> 2. Is it safe that one
> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,

Just add new rules is safe, but applying them (calling rte_acl_build()) is not.
Konstantin

=?gb18030?b?u9i4tKO6UkU6ILvYuLSjulJFOiAgVGhyZWFkIHNh?= =?gb18030?q?fety_in_rte=5Facl?=

[=?gb18030?B?1ebO0rfnssk=?=]

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>> 2. Is it safe that one
>> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,

>Just add new rules is safe, but applying them (calling rte_acl_build()) is not.

> In my case, there are two process sharing hugepage memory£¨struct rte_acl_ctx£©,  one process call 'rte_acl_build' to add and apply rule, another process call  frequently 'rte_acl_classify' to > match rule, does it need to add lock? if not, is there other method to implement this safely?

>Yes, you'll need some sort of synchronization.
>Lock (or rwlock) is one option, but as build could take quite long time - probably not the best one.
>Another way - have a struct cthat ontains pointers to 2 ctx and an index for active one.
>Then you can do classify() on active one while doing add_rules/build on second one.
>Then when the second one is re-build you can switch an active index to it.
>I think librte_table uses that method.
>Of course you might need a reference counter or some other way to deternine that
>no-one is using old copy anymore and it is free to update it again.
>Konstantin 


thanks very much
------------------ ԭʼÓʼþ ------------------
·¢¼þÈË: "Ananyev, Konstantin";<konstantin.ananyev@intel.com>;
·¢ËÍʱ¼ä: 2018Äê1ÔÂ8ÈÕ(ÐÇÆÚÒ») ÍíÉÏ8:17
ÊÕ¼þÈË: "ÕæÎÒ·ç²É"<1534057243@qq.com>;"dev"<dev@dpdk.org>;

Ö÷Ìâ: RE: »Ø¸´£ºRE: [dpdk-dev] Thread safety in rte_acl






>> 2. Is it safe that one
>> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,

>Just add new rules is safe, but applying them (calling rte_acl_build()) is not.

> In my case, there are two process sharing hugepage memory£¨struct rte_acl_ctx£©,  one process call 'rte_acl_build' to add and apply rule, another process call  frequently 'rte_acl_classify' to > match rule, does it need to add lock? if not, is there other method to implement this safely?

Yes, you'll need some sort of synchronization.
Lock (or rwlock) is one option, but as build could take quite long time - probably not the best one.
Another way - have a struct cthat ontains pointers to 2 ctx and an index for active one.
Then you can do classify() on active one while doing add_rules/build on second one.
Then when the second one is re-build you can switch an active index to it.
I think librte_table uses that method.
Of course you might need a reference counter or some other way to deternine that
no-one is using old copy anymore and it is free to update it again.
Konstantin 


------------------ ԭʼÓʼþ ------------------
·¢¼þÈË: "Ananyev, Konstantin";<konstantin.ananyev@intel.com>;
·¢ËÍʱ¼ä: 2018Äê1ÔÂ8ÈÕ(ÐÇÆÚÒ») ÍíÉÏ7:42
ÊÕ¼þÈË: "ÕæÎÒ·ç²É"<1534057243@qq.com>;"dev"<dev@dpdk.org>;
Ö÷Ìâ: RE: [dpdk-dev] Thread safety in rte_acl

> 
> Hi, I have two questions : 1. Is it safe that multiple threads will run "rte_acl_classify" in parallel  (on the same ctx )?

Yes.

> 2. Is it safe that one
> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,

Just add new rules is safe, but applying them (calling rte_acl_build()) is not.
Konstantin

=?gb18030?b?u9i4tKO6UkU6ILvYuLSjulJFOiAgVGhyZWFkIHNh?= =?gb18030?q?fety_in_rte=5Facl?=

[=?gb18030?B?1ebO0rfnssk=?=]

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>Yes, you'll need some sort of synchronization.
>Lock (or rwlock) is one option, but as build could take quite long time - probably not the best one.
>Another way - have a struct cthat ontains pointers to 2 ctx and an index for active one.
>Then you can do classify() on active one while doing add_rules/build on second one.
>Then when the second one is re-build you can switch an active index to it.
>I think librte_table uses that method.
>Of course you might need a reference counter or some other way to deternine that
>no-one is using old copy anymore and it is free to update it again.
>Konstantin 


I have look at the source of samplevnf as below doc, it switchover active and standby directlt without ensuring old copy not used anymore.
https://github.com/opnfv/samplevnf/blob/master/VNFs/vACL/pipeline/pipeline_acl.c: cmd_acl_applyruleset_parsed


So, my question is that how to ensure that no-one is using old copy anymore ? 


thanks!
------------------ ԭʼÓʼþ ------------------
·¢¼þÈË: "Ananyev, Konstantin";<konstantin.ananyev@intel.com>;
·¢ËÍʱ¼ä: 2018Äê1ÔÂ8ÈÕ(ÐÇÆÚÒ») ÍíÉÏ8:17
ÊÕ¼þÈË: "ÕæÎÒ·ç²É"<1534057243@qq.com>;"dev"<dev@dpdk.org>;

Ö÷Ìâ: RE: »Ø¸´£ºRE: [dpdk-dev] Thread safety in rte_acl






>> 2. Is it safe that one
>> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,

>Just add new rules is safe, but applying them (calling rte_acl_build()) is not.

> In my case, there are two process sharing hugepage memory£¨struct rte_acl_ctx£©,  one process call 'rte_acl_build' to add and apply rule, another process call  frequently 'rte_acl_classify' to > match rule, does it need to add lock? if not, is there other method to implement this safely?

Yes, you'll need some sort of synchronization.
Lock (or rwlock) is one option, but as build could take quite long time - probably not the best one.
Another way - have a struct cthat ontains pointers to 2 ctx and an index for active one.
Then you can do classify() on active one while doing add_rules/build on second one.
Then when the second one is re-build you can switch an active index to it.
I think librte_table uses that method.
Of course you might need a reference counter or some other way to deternine that
no-one is using old copy anymore and it is free to update it again.
Konstantin 


------------------ ԭʼÓʼþ ------------------
·¢¼þÈË: "Ananyev, Konstantin";<konstantin.ananyev@intel.com>;
·¢ËÍʱ¼ä: 2018Äê1ÔÂ8ÈÕ(ÐÇÆÚÒ») ÍíÉÏ7:42
ÊÕ¼þÈË: "ÕæÎÒ·ç²É"<1534057243@qq.com>;"dev"<dev@dpdk.org>;
Ö÷Ìâ: RE: [dpdk-dev] Thread safety in rte_acl

> 
> Hi, I have two questions : 1. Is it safe that multiple threads will run "rte_acl_classify" in parallel  (on the same ctx )?

Yes.

> 2. Is it safe that one
> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,

Just add new rules is safe, but applying them (calling rte_acl_build()) is not.
Konstantin

Re: 回复：RE: 回复：RE: Thread safety in rte_acl

[Ramia, Kannan Babu]

The way the application is written assumes there will be a transition phase where few threads will have OLD ACL results for the packets that are currently handled, but once those set is flushed out all the new set of packets will be back to the active set. So the system will be consistent after this transition period.

PS: Please also look at the vCG-NAT and vFW to see how this could be achieved in the application.

Regards
Kannan Babu

From: 真我风采 [mailto:1534057243@qq.com]
Sent: Wednesday, January 10, 2018 8:20 AM
To: Ananyev, Konstantin <konstantin.ananyev@intel.com>; Ramia, Kannan Babu <kannan.babu.ramia@intel.com>; dev <dev@dpdk.org>
Subject: 回复：RE: 回复：RE: [dpdk-dev] Thread safety in rte_acl


>Yes, you'll need some sort of synchronization.
>Lock (or rwlock) is one option, but as build could take quite long time - probably not the best one.
>Another way - have a struct cthat ontains pointers to 2 ctx and an index for active one.
>Then you can do classify() on active one while doing add_rules/build on second one.
>Then when the second one is re-build you can switch an active index to it.
>I think librte_table uses that method.
>Of course you might need a reference counter or some other way to deternine that
>no-one is using old copy anymore and it is free to update it again.
>Konstantin

I have look at the source of samplevnf as below doc, it switchover active and standby directlt without ensuring old copy not used anymore.
https://github.com/opnfv/samplevnf/blob/master/VNFs/vACL/pipeline/pipeline_acl.c: cmd_acl_applyruleset_parsed

So, my question is that how to ensure that no-one is using old copy anymore ?

thanks!
------------------ 原始邮件 ------------------
发件人: "Ananyev, Konstantin";<konstantin.ananyev@intel.com<mailto:konstantin.ananyev@intel.com>>;
发送时间: 2018年1月8日(星期一) 晚上8:17
收件人: "真我风采"<1534057243@qq.com<mailto:1534057243@qq.com>>;"dev"<dev@dpdk.org<mailto:dev@dpdk.org>>;
主题: RE: 回复：RE: [dpdk-dev] Thread safety in rte_acl




>> 2. Is it safe that one
>> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,

>Just add new rules is safe, but applying them (calling rte_acl_build()) is not.

> In my case, there are two process sharing hugepage memory（struct rte_acl_ctx）,  one process call 'rte_acl_build' to add and apply rule, another process call  frequently 'rte_acl_classify' to > match rule, does it need to add lock? if not, is there other method to implement this safely?

Yes, you'll need some sort of synchronization.
Lock (or rwlock) is one option, but as build could take quite long time - probably not the best one.
Another way - have a struct cthat ontains pointers to 2 ctx and an index for active one.
Then you can do classify() on active one while doing add_rules/build on second one.
Then when the second one is re-build you can switch an active index to it.
I think librte_table uses that method.
Of course you might need a reference counter or some other way to deternine that
no-one is using old copy anymore and it is free to update it again.
Konstantin


------------------ 原始邮件 ------------------
发件人: "Ananyev, Konstantin";<konstantin.ananyev@intel.com<mailto:konstantin.ananyev@intel.com>>;
发送时间: 2018年1月8日(星期一) 晚上7:42
收件人: "真我风采"<1534057243@qq.com<mailto:1534057243@qq.com>>;"dev"<dev@dpdk.org<mailto:dev@dpdk.org>>;
主题: RE: [dpdk-dev] Thread safety in rte_acl

>
> Hi, I have two questions : 1. Is it safe that multiple threads will run "rte_acl_classify" in parallel  (on the same ctx )?

Yes.

> 2. Is it safe that one
> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,

Just add new rules is safe, but applying them (calling rte_acl_build()) is not.
Konstantin

Re: 回复：RE: 回复：RE: Thread safety in rte_acl

[Ananyev, Konstantin]

The simplest one would be to have rwlock to read/write active index.
Also something like that I think should work (just a sample, not tested or compiled):

struct acl {
       rte_acl_ctx *ctx[2];
       rte_atomic32_t use;
       uint32_t active;
};

update(struct acl *acl, …)
{
   <update/rebuild  non-acive copy>
   /* make sure all stores are visible */
   rte_smp_wmb();

   uint32_t  active = acl->active;
   acl->active = active ^ 1;
    /* to avoid store/load reorder */
   rte_smp_mb();

   while (rte_atomic32_read(&acl->use) != 0)
      rte_pause();

   <free old active copy here>
}

classify(struct acl *acl, …)
{
     rte_atomic32_inc(&acl->use);
     rte_acl_classify(acl->ctx[acl->active}, …);
     rte_atomic32_dec(&acl->use);
}

Konstantin

From: 真我风采 [mailto:1534057243@qq.com]
Sent: Wednesday, January 10, 2018 2:50 AM
To: Ananyev, Konstantin <konstantin.ananyev@intel.com>; Ramia, Kannan Babu <kannan.babu.ramia@intel.com>; dev <dev@dpdk.org>
Subject: 回复：RE: 回复：RE: [dpdk-dev] Thread safety in rte_acl


>Yes, you'll need some sort of synchronization.
>Lock (or rwlock) is one option, but as build could take quite long time - probably not the best one.
>Another way - have a struct cthat ontains pointers to 2 ctx and an index for active one.
>Then you can do classify() on active one while doing add_rules/build on second one.
>Then when the second one is re-build you can switch an active index to it.
>I think librte_table uses that method.
>Of course you might need a reference counter or some other way to deternine that
>no-one is using old copy anymore and it is free to update it again.
>Konstantin

I have look at the source of samplevnf as below doc, it switchover active and standby directlt without ensuring old copy not used anymore.
https://github.com/opnfv/samplevnf/blob/master/VNFs/vACL/pipeline/pipeline_acl.c: cmd_acl_applyruleset_parsed

So, my question is that how to ensure that no-one is using old copy anymore ?

thanks!
------------------ 原始邮件 ------------------
发件人: "Ananyev, Konstantin";<konstantin.ananyev@intel.com<mailto:konstantin.ananyev@intel.com>>;
发送时间: 2018年1月8日(星期一) 晚上8:17
收件人: "真我风采"<1534057243@qq.com<mailto:1534057243@qq.com>>;"dev"<dev@dpdk.org<mailto:dev@dpdk.org>>;
主题: RE: 回复：RE: [dpdk-dev] Thread safety in rte_acl




>> 2. Is it safe that one
>> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,

>Just add new rules is safe, but applying them (calling rte_acl_build()) is not.

> In my case, there are two process sharing hugepage memory（struct rte_acl_ctx）,  one process call 'rte_acl_build' to add and apply rule, another process call  frequently 'rte_acl_classify' to > match rule, does it need to add lock? if not, is there other method to implement this safely?

Yes, you'll need some sort of synchronization.
Lock (or rwlock) is one option, but as build could take quite long time - probably not the best one.
Another way - have a struct cthat ontains pointers to 2 ctx and an index for active one.
Then you can do classify() on active one while doing add_rules/build on second one.
Then when the second one is re-build you can switch an active index to it.
I think librte_table uses that method.
Of course you might need a reference counter or some other way to deternine that
no-one is using old copy anymore and it is free to update it again.
Konstantin


------------------ 原始邮件 ------------------
发件人: "Ananyev, Konstantin";<konstantin.ananyev@intel.com<mailto:konstantin.ananyev@intel.com>>;
发送时间: 2018年1月8日(星期一) 晚上7:42
收件人: "真我风采"<1534057243@qq.com<mailto:1534057243@qq.com>>;"dev"<dev@dpdk.org<mailto:dev@dpdk.org>>;
主题: RE: [dpdk-dev] Thread safety in rte_acl

>
> Hi, I have two questions : 1. Is it safe that multiple threads will run "rte_acl_classify" in parallel  (on the same ctx )?

Yes.

> 2. Is it safe that one
> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,

Just add new rules is safe, but applying them (calling rte_acl_build()) is not.
Konstantin

=?gb18030?b?u9i4tKO6UkU6ILvYuLSjulJFOiC72Li0o7pSRTog?= =?gb18030?q?_Thread_safety_in_rte=5Facl?=

[=?gb18030?B?1ebO0rfnssk=?=]

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Thanks for providing idea to me! I will refer to that.


I have another way feeling that it should works too. switchover active and standby pointer on forward plane, rather than on control plane. when update ctx in control plane(add rule, build on standby, meanwhile add rule on active not build), set flag=1, and on forward plane if flag==1 then switchover and set flag=0. 










------------------ ԭʼÓʼþ ------------------
·¢¼þÈË: "Ananyev, Konstantin";<konstantin.ananyev@intel.com>;
·¢ËÍʱ¼ä: 2018Äê1ÔÂ10ÈÕ(ÐÇÆÚÈý) ÍíÉÏ7:46
ÊÕ¼þÈË: "ÕæÎÒ·ç²É"<1534057243@qq.com>;"Ramia, Kannan Babu"<kannan.babu.ramia@intel.com>;"dev"<dev@dpdk.org>;

Ö÷Ìâ: RE: »Ø¸´£ºRE: »Ø¸´£ºRE: [dpdk-dev] Thread safety in rte_acl



  
 
 
The simplest one would be to have rwlock to read/write active index.
 
Also something like that I think should work (just a sample, not tested or compiled):
 
 
 
struct acl {
 
       rte_acl_ctx *ctx[2];
 
       rte_atomic32_t use;
 
       uint32_t active;
 
};
 
 
 
update(struct acl *acl, ¡­)
 
{
 
   <update/rebuild  non-acive copy>
 
   /* make sure all stores are visible */
 
   rte_smp_wmb();
 
   
 
   uint32_t  active = acl->active;
 
   acl->active = active ^ 1;
 

 
    /* to avoid store/load reorder */
 
   rte_smp_mb();
 
 
 
   while (rte_atomic32_read(&acl->use) != 0)
 
      rte_pause();
 
   
 
   <free old active copy here>
 
}
 
 
 
classify(struct acl *acl, ¡­)
 
{
 
     rte_atomic32_inc(&acl->use);
 
     rte_acl_classify(acl->ctx[acl->active}, ¡­);
 
     rte_atomic32_dec(&acl->use);
 
}
 
 
 
Konstantin
 
 
    
From: ÕæÎÒ·ç²É [mailto:1534057243@qq.com] 
 Sent: Wednesday, January 10, 2018 2:50 AM
 To: Ananyev, Konstantin <konstantin.ananyev@intel.com>; Ramia, Kannan Babu <kannan.babu.ramia@intel.com>; dev <dev@dpdk.org>
 Subject: »Ø¸´£ºRE: »Ø¸´£ºRE: [dpdk-dev] Thread safety in rte_acl
 
 
 
 
  

 >Yes, you'll need some sort of synchronization.
 >Lock (or rwlock) is one option, but as build could take quite long time - probably not the best one.
 >Another way - have a struct cthat ontains pointers to 2 ctx and an index for active one.
 >Then you can do classify() on active one while doing add_rules/build on second one.
 >Then when the second one is re-build you can switch an active index to it.
 >I think librte_table uses that method.
 >Of course you might need a reference counter or some other way to deternine that
 >no-one is using old copy anymore and it is free to update it again.
 >Konstantin 
 
   
 
 
  
I have look at the source of samplevnf as below doc, it switchover active and standby directlt without ensuring old copy not used anymore.
 
  
https://github.com/opnfv/samplevnf/blob/master/VNFs/vACL/pipeline/pipeline_acl.c: cmd_acl_applyruleset_parsed
 
  
 
 
  
So, my question is that how to ensure that no-one is using old copy anymore ? 
 
  
 
 
  
thanks!
 
  
------------------ ԭʼÓʼþ ------------------
 
   
·¢¼þÈË: "Ananyev, Konstantin";<konstantin.ananyev@intel.com>;
 
  
·¢ËÍʱ¼ä: 2018Äê1ÔÂ8ÈÕ(ÐÇÆÚÒ») ÍíÉÏ8:17
 
  
ÊÕ¼þÈË: "ÕæÎÒ·ç²É"<1534057243@qq.com>;"dev"<dev@dpdk.org>;
 
  
Ö÷Ìâ: RE: »Ø¸´£ºRE: [dpdk-dev] Thread safety in rte_acl
 
 
  
 
 
 

 
 
 >> 2. Is it safe that one
 >> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,
 
 >Just add new rules is safe, but applying them (calling rte_acl_build()) is not.
 
 > In my case, there are two process sharing hugepage memory£¨struct rte_acl_ctx£©,  one process call 'rte_acl_build' to add and apply rule, another process  call  frequently 'rte_acl_classify' to > match rule, does it need to add lock? if not, is there other method to implement this safely?
 
 Yes, you'll need some sort of synchronization.
 Lock (or rwlock) is one option, but as build could take quite long time - probably not the best one.
 Another way - have a struct cthat ontains pointers to 2 ctx and an index for active one.
 Then you can do classify() on active one while doing add_rules/build on second one.
 Then when the second one is re-build you can switch an active index to it.
 I think librte_table uses that method.
 Of course you might need a reference counter or some other way to deternine that
 no-one is using old copy anymore and it is free to update it again.
 Konstantin 
 
 
 ------------------ ԭʼÓʼþ ------------------
 ·¢¼þÈË: "Ananyev, Konstantin";<konstantin.ananyev@intel.com>;
 ·¢ËÍʱ¼ä: 2018Äê1ÔÂ8ÈÕ(ÐÇÆÚÒ») ÍíÉÏ7:42
 ÊÕ¼þÈË: "ÕæÎÒ·ç²É"<1534057243@qq.com>;"dev"<dev@dpdk.org>;
 Ö÷Ìâ: RE: [dpdk-dev] Thread safety in rte_acl
 
 > 
 > Hi, I have two questions : 1. Is it safe that multiple threads will run "rte_acl_classify" in parallel  (on the same ctx )?
 
 Yes.
 
 > 2. Is it safe that one
 > thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,
 
 Just add new rules is safe, but applying them (calling rte_acl_build()) is not.
 Konstantin

Re: 回复：RE: 回复：RE: 回复：RE: Thread safety in rte_acl

[Ananyev, Konstantin]

That should work too I think…
But in that case your data-plane would have to grab exclusive lock
(in case you have multiple threads/processes) doing classify()
over the same context in parallel.
Konstantin

From: 真我风采 [mailto:1534057243@qq.com]
Sent: Monday, January 15, 2018 2:01 AM
To: Ananyev, Konstantin <konstantin.ananyev@intel.com>; Ramia, Kannan Babu <kannan.babu.ramia@intel.com>; dev <dev@dpdk.org>
Subject: 回复：RE: 回复：RE: 回复：RE: [dpdk-dev] Thread safety in rte_acl

Thanks for providing idea to me! I will refer to that.

I have another way feeling that it should works too. switchover active and standby pointer on forward plane, rather than on control plane. when update ctx in control plane(add rule, build on standby, meanwhile add rule on active not build), set flag=1, and on forward plane if flag==1 then switchover and set flag=0.





------------------ 原始邮件 ------------------
发件人: "Ananyev, Konstantin";<konstantin.ananyev@intel.com<mailto:konstantin.ananyev@intel.com>>;
发送时间: 2018年1月10日(星期三) 晚上7:46
收件人: "真我风采"<1534057243@qq.com<mailto:1534057243@qq.com>>;"Ramia, Kannan Babu"<kannan.babu.ramia@intel.com<mailto:kannan.babu.ramia@intel.com>>;"dev"<dev@dpdk.org<mailto:dev@dpdk.org>>;
主题: RE: 回复：RE: 回复：RE: [dpdk-dev] Thread safety in rte_acl


The simplest one would be to have rwlock to read/write active index.
Also something like that I think should work (just a sample, not tested or compiled):

struct acl {
       rte_acl_ctx *ctx[2];
       rte_atomic32_t use;
       uint32_t active;
};

update(struct acl *acl, …)
{
   <update/rebuild  non-acive copy>
   /* make sure all stores are visible */
   rte_smp_wmb();

   uint32_t  active = acl->active;
   acl->active = active ^ 1;
    /* to avoid store/load reorder */
   rte_smp_mb();

   while (rte_atomic32_read(&acl->use) != 0)
      rte_pause();

   <free old active copy here>
}

classify(struct acl *acl, …)
{
     rte_atomic32_inc(&acl->use);
     rte_acl_classify(acl->ctx[acl->active}, …);
     rte_atomic32_dec(&acl->use);
}

Konstantin

From: 真我风采 [mailto:1534057243@qq.com]
Sent: Wednesday, January 10, 2018 2:50 AM
To: Ananyev, Konstantin <konstantin.ananyev@intel.com<mailto:konstantin.ananyev@intel.com>>; Ramia, Kannan Babu <kannan.babu.ramia@intel.com<mailto:kannan.babu.ramia@intel.com>>; dev <dev@dpdk.org<mailto:dev@dpdk.org>>
Subject: 回复：RE: 回复：RE: [dpdk-dev] Thread safety in rte_acl


>Yes, you'll need some sort of synchronization.
>Lock (or rwlock) is one option, but as build could take quite long time - probably not the best one.
>Another way - have a struct cthat ontains pointers to 2 ctx and an index for active one.
>Then you can do classify() on active one while doing add_rules/build on second one.
>Then when the second one is re-build you can switch an active index to it.
>I think librte_table uses that method.
>Of course you might need a reference counter or some other way to deternine that
>no-one is using old copy anymore and it is free to update it again.
>Konstantin

I have look at the source of samplevnf as below doc, it switchover active and standby directlt without ensuring old copy not used anymore.
https://github.com/opnfv/samplevnf/blob/master/VNFs/vACL/pipeline/pipeline_acl.c: cmd_acl_applyruleset_parsed

So, my question is that how to ensure that no-one is using old copy anymore ?

thanks!
------------------ 原始邮件 ------------------
发件人: "Ananyev, Konstantin";<konstantin.ananyev@intel.com<mailto:konstantin.ananyev@intel.com>>;
发送时间: 2018年1月8日(星期一) 晚上8:17
收件人: "真我风采"<1534057243@qq.com<mailto:1534057243@qq.com>>;"dev"<dev@dpdk.org<mailto:dev@dpdk.org>>;
主题: RE: 回复：RE: [dpdk-dev] Thread safety in rte_acl




>> 2. Is it safe that one
>> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,

>Just add new rules is safe, but applying them (calling rte_acl_build()) is not.

> In my case, there are two process sharing hugepage memory（struct rte_acl_ctx）,  one process call 'rte_acl_build' to add and apply rule, another process call  frequently 'rte_acl_classify' to > match rule, does it need to add lock? if not, is there other method to implement this safely?

Yes, you'll need some sort of synchronization.
Lock (or rwlock) is one option, but as build could take quite long time - probably not the best one.
Another way - have a struct cthat ontains pointers to 2 ctx and an index for active one.
Then you can do classify() on active one while doing add_rules/build on second one.
Then when the second one is re-build you can switch an active index to it.
I think librte_table uses that method.
Of course you might need a reference counter or some other way to deternine that
no-one is using old copy anymore and it is free to update it again.
Konstantin


------------------ 原始邮件 ------------------
发件人: "Ananyev, Konstantin";<konstantin.ananyev@intel.com<mailto:konstantin.ananyev@intel.com>>;
发送时间: 2018年1月8日(星期一) 晚上7:42
收件人: "真我风采"<1534057243@qq.com<mailto:1534057243@qq.com>>;"dev"<dev@dpdk.org<mailto:dev@dpdk.org>>;
主题: RE: [dpdk-dev] Thread safety in rte_acl

>
> Hi, I have two questions : 1. Is it safe that multiple threads will run "rte_acl_classify" in parallel  (on the same ctx )?

Yes.

> 2. Is it safe that one
> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,

Just add new rules is safe, but applying them (calling rte_acl_build()) is not.
Konstantin

=?gb18030?b?u9i4tKO6UkU6ILvYuLSjulJFOiC72Li0o7pSRTogu9i4tKO6UkU6ICBUaHJlYWQgc2FmZXR5IGluIHJ0ZV9hY2w=?=

[=?gb18030?B?1ebO0rfnssk=?=]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="gb18030", Size: 6202 bytes --]

Yes£¬ but now there is only one process doing classify() in our case, so it just suitable.


thanks !!!




------------------ ԭʼÓʼþ ------------------
·¢¼þÈË: "Ananyev, Konstantin";<konstantin.ananyev@intel.com>;
·¢ËÍʱ¼ä: 2018Äê1ÔÂ15ÈÕ(ÐÇÆÚÒ») ÍíÉÏ6:34
ÊÕ¼þÈË: "ÕæÎÒ·ç²É"<1534057243@qq.com>;"Ramia, Kannan Babu"<kannan.babu.ramia@intel.com>;"dev"<dev@dpdk.org>;

Ö÷Ìâ: RE: »Ø¸´£ºRE: »Ø¸´£ºRE: »Ø¸´£ºRE: [dpdk-dev] Thread safety in rte_acl



  
That should work too I think¡­
 
But in that case your data-plane would have to grab exclusive lock
 
(in case you have multiple threads/processes) doing classify()
 
over the same context in parallel.
 
Konstantin
 
 
    
From: ÕæÎÒ·ç²É [mailto:1534057243@qq.com] 
 Sent: Monday, January 15, 2018 2:01 AM
 To: Ananyev, Konstantin <konstantin.ananyev@intel.com>; Ramia, Kannan Babu <kannan.babu.ramia@intel.com>; dev <dev@dpdk.org>
 Subject: »Ø¸´£ºRE: »Ø¸´£ºRE: »Ø¸´£ºRE: [dpdk-dev] Thread safety in rte_acl
 
 
 
 
  
Thanks for providing idea to me! I will refer to that.
 
  
 
 
  
I have another way feeling that it should works too. switchover active and standby pointer on forward plane, rather than on control plane. when update ctx in control plane(add rule, build on standby, meanwhile add rule on active not build),  set flag=1, and on forward plane if flag==1 then switchover and set flag=0. 
 
  
 
 
  
 
 
  
 
 
   
 
 
  
 
 
  
------------------ ԭʼÓʼþ ------------------
 
   
·¢¼þÈË: "Ananyev, Konstantin";<konstantin.ananyev@intel.com>;
 
  
·¢ËÍʱ¼ä: 2018Äê1ÔÂ10ÈÕ(ÐÇÆÚÈý) ÍíÉÏ7:46
 
  
ÊÕ¼þÈË: "ÕæÎÒ·ç²É"<1534057243@qq.com>;"Ramia,  Kannan Babu"<kannan.babu.ramia@intel.com>;"dev"<dev@dpdk.org>;
 
  
Ö÷Ìâ: RE: »Ø¸´£ºRE: »Ø¸´£ºRE: [dpdk-dev] Thread safety in rte_acl
 
 
  
 
 
  
 
 
The simplest one would be to have rwlock to read/write active index.
 
Also something like that I think should work (just a sample, not tested or compiled):
 
 
 
struct acl {
 
       rte_acl_ctx *ctx[2];
 
       rte_atomic32_t use;
 
       uint32_t active;
 
};
 
 
 
update(struct acl *acl, ¡­)
 
{
 
   <update/rebuild  non-acive copy>
 
   /* make sure all stores are visible */
 
   rte_smp_wmb();
 
  
 
   uint32_t  active = acl->active;
 
   acl->active = active ^ 1;
 
    /* to avoid store/load reorder */
 
   rte_smp_mb();
 
 
 
   while (rte_atomic32_read(&acl->use) != 0)
 
      rte_pause();
 
  
 
   <free old active copy here>
 
}
 
 
 
classify(struct acl *acl, ¡­)
 
{
 
     rte_atomic32_inc(&acl->use);
 
     rte_acl_classify(acl->ctx[acl->active}, ¡­);
 
     rte_atomic32_dec(&acl->use);
 
}
 
 
 
Konstantin
 
 
    
From:  ÕæÎÒ·ç²É [mailto:1534057243@qq.com] 
 Sent: Wednesday, January 10, 2018 2:50 AM
 To: Ananyev, Konstantin <konstantin.ananyev@intel.com>; Ramia, Kannan Babu <kannan.babu.ramia@intel.com>; dev <dev@dpdk.org>
 Subject:  »Ø¸´£ºRE:  »Ø¸´£ºRE: [dpdk-dev] Thread safety in rte_acl
 
 
 
 
  

 >Yes, you'll need some sort of synchronization.
 >Lock (or rwlock) is one option, but as build could take quite long time - probably not the best one.
 >Another way - have a struct cthat ontains pointers to 2 ctx and an index for active one.
 >Then you can do classify() on active one while doing add_rules/build on second one.
 >Then when the second one is re-build you can switch an active index to it.
 >I think librte_table uses that method.
 >Of course you might need a reference counter or some other way to deternine that
 >no-one is using old copy anymore and it is free to update it again.
 >Konstantin 
 
   
 
 
  
I have look at the source of samplevnf as below doc, it switchover active and standby directlt without ensuring old copy not used anymore.
 
  
https://github.com/opnfv/samplevnf/blob/master/VNFs/vACL/pipeline/pipeline_acl.c: cmd_acl_applyruleset_parsed
 
  
 
 
  
So, my question is that how to ensure that no-one is using old copy anymore ? 
 
  
 
 
  
thanks!
 
  
------------------ ԭʼÓʼþ ------------------
 
   
 ·¢¼þÈË: "Ananyev, Konstantin";<konstantin.ananyev@intel.com>;
 
  
 ·¢ËÍʱ¼ä: 2018Äê1ÔÂ8ÈÕ(ÐÇÆÚÒ») ÍíÉÏ8:17
 
  
 ÊÕ¼þÈË: "ÕæÎÒ·ç²É"<1534057243@qq.com>;"dev"<dev@dpdk.org>;
 
  
 Ö÷Ìâ: RE: »Ø¸´£ºRE: [dpdk-dev] Thread safety in rte_acl
 
 
  
 
 
 

 
 
 >> 2. Is it safe that one
 >> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,
 
 >Just add new rules is safe, but applying them (calling rte_acl_build()) is not.
 
 > In my case, there are two process sharing hugepage memory£¨struct rte_acl_ctx£©,  one process call 'rte_acl_build' to add and apply rule, another process  call  frequently 'rte_acl_classify' to > match rule, does it need to add lock? if not, is there other method to implement this safely?
 
 Yes, you'll need some sort of synchronization.
 Lock (or rwlock) is one option, but as build could take quite long time - probably not the best one.
 Another way - have a struct cthat ontains pointers to 2 ctx and an index for active one.
 Then you can do classify() on active one while doing add_rules/build on second one.
 Then when the second one is re-build you can switch an active index to it.
 I think librte_table uses that method.
 Of course you might need a reference counter or some other way to deternine that
 no-one is using old copy anymore and it is free to update it again.
 Konstantin 
 
 
 ------------------ ԭʼÓʼþ ------------------
 ·¢¼þÈË: "Ananyev, Konstantin";<konstantin.ananyev@intel.com>;
 ·¢ËÍʱ¼ä: 2018Äê1ÔÂ8ÈÕ(ÐÇÆÚÒ») ÍíÉÏ7:42
 ÊÕ¼þÈË: "ÕæÎÒ·ç²É"<1534057243@qq.com>;"dev"<dev@dpdk.org>;
 Ö÷Ìâ: RE: [dpdk-dev] Thread safety in rte_acl
 
 > 
 > Hi, I have two questions : 1. Is it safe that multiple threads will run "rte_acl_classify" in parallel  (on the same ctx )?
 
 Yes.
 
 > 2. Is it safe that one
 > thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,
 
 Just add new rules is safe, but applying them (calling rte_acl_build()) is not.
 Konstantin

Re: 回复：RE: Thread safety in rte_acl

[Ramia, Kannan Babu]

You can look at the source of anyone of the applications in samplevnf project in OPNFV which uses the active/shadow method for dynamically modifying the rules and applying them.

Regards
Kannan Babu

-----Original Message-----
From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of ????
Sent: Monday, January 8, 2018 5:30 PM
To: Ananyev, Konstantin <konstantin.ananyev@intel.com>; dev <dev@dpdk.org>
Subject: [dpdk-dev] 回复：RE: Thread safety in rte_acl

>> 2. Is it safe that one
>> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,

>Just add new rules is safe, but applying them (calling rte_acl_build()) is not.


In my case, there are two process sharing hugepage memory（struct rte_acl_ctx）,  one process call 'rte_acl_build' to add and apply rule, another process call  frequently 'rte_acl_classify' to match rule, does it need to add lock? if not, is there other method to implement this safely?


------------------ 原始邮件 ------------------
发件人: "Ananyev, Konstantin";<konstantin.ananyev@intel.com>;
发送时间: 2018年1月8日(星期一) 晚上7:42
收件人: "真我风采"<1534057243@qq.com>;"dev"<dev@dpdk.org>;

主题: RE: [dpdk-dev] Thread safety in rte_acl



> 
> Hi, I have two questions : 1. Is it safe that multiple threads will run "rte_acl_classify" in parallel  (on the same ctx )?

Yes.

> 2. Is it safe that one
> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,

Just add new rules is safe, but applying them (calling rte_acl_build()) is not.
Konstantin

=?gb18030?b?u9i4tKO6UkU6ICC72Li0o7pSRTogIFRocmVhZCBz?= =?gb18030?q?afety_in_rte=5Facl?=

[=?gb18030?B?1ebO0rfnssk=?=]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="gb18030", Size: 1961 bytes --]

Thanks very much!




------------------ ԭʼÓʼþ ------------------
·¢¼þÈË: "Ramia, Kannan Babu";<kannan.babu.ramia@intel.com>;
·¢ËÍʱ¼ä: 2018Äê1ÔÂ8ÈÕ(ÐÇÆÚÒ») ÍíÉÏ9:06
ÊÕ¼þÈË: "ÕæÎÒ·ç²É"<1534057243@qq.com>;"Ananyev, Konstantin"<konstantin.ananyev@intel.com>;"dev"<dev@dpdk.org>;

Ö÷Ìâ: RE: [dpdk-dev] »Ø¸´£ºRE:  Thread safety in rte_acl



You can look at the source of anyone of the applications in samplevnf project in OPNFV which uses the active/shadow method for dynamically modifying the rules and applying them.

Regards
Kannan Babu

-----Original Message-----
From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of ????
Sent: Monday, January 8, 2018 5:30 PM
To: Ananyev, Konstantin <konstantin.ananyev@intel.com>; dev <dev@dpdk.org>
Subject: [dpdk-dev] »Ø¸´£ºRE: Thread safety in rte_acl

>> 2. Is it safe that one
>> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,

>Just add new rules is safe, but applying them (calling rte_acl_build()) is not.


In my case, there are two process sharing hugepage memory£¨struct rte_acl_ctx£©,  one process call 'rte_acl_build' to add and apply rule, another process call  frequently 'rte_acl_classify' to match rule, does it need to add lock? if not, is there other method to implement this safely?


------------------ ԭʼÓʼþ ------------------
·¢¼þÈË: "Ananyev, Konstantin";<konstantin.ananyev@intel.com>;
·¢ËÍʱ¼ä: 2018Äê1ÔÂ8ÈÕ(ÐÇÆÚÒ») ÍíÉÏ7:42
ÊÕ¼þÈË: "ÕæÎÒ·ç²É"<1534057243@qq.com>;"dev"<dev@dpdk.org>;

Ö÷Ìâ: RE: [dpdk-dev] Thread safety in rte_acl



> 
> Hi, I have two questions : 1. Is it safe that multiple threads will run "rte_acl_classify" in parallel  (on the same ctx )?

Yes.

> 2. Is it safe that one
> thread will run  "rte_acl_classify" when another thread tries to add new rules to same ctx? thanks,

Just add new rules is safe, but applying them (calling rte_acl_build()) is not.
Konstantin