[Lustre-devel] lustre-to-LNET API: big non-aligned bulk transfers

[Lustre-devel] lustre-to-LNET API: big non-aligned bulk transfers

[Maxim V. Patlasov]

Hi lustre-devel,

I'd like to gather some opinions about the following question:

Is it allowed or possible for lustre to submit relatively big bulk 
transfer request (e.g. >512K) to LNET layer when offset in the very 
first page to fetch bulk data from (on sender side) is not equal to the 
offset in the very first page to store data (on receiver side)? In the 
other words - should LNET support such transfers?

Thanks in advance,
Maxim

[Lustre-devel] lustre-to-LNET API: big non-aligned bulk transfers

[Eric Barton]

Maxim,

It should support such transfers, but you have to be careful about
the number of fragments this can introduce.  This issue has already
been observed in routers, which buffer LNET message payloads at
the same page offset, irrespective of the sender's page offset (of
which it has no knowledge).  For example, this can force the o2iblnd,
if configured to pre-map all memory, to need double the number of RDMA
fragments and therefore fail the transfer.  Chat with Liang - he knows
all about this...

    Cheers,
              Eric

> -----Original Message-----
> From: lustre-devel-bounces at lists.lustre.org [mailto:lustre-devel-bounces at lists.lustre.org] On Behalf Of Maxim V.
> Patlasov
> Sent: 14 October 2009 8:23 AM
> To: lustre-devel at lists.lustre.org
> Subject: [Lustre-devel] lustre-to-LNET API: big non-aligned bulk transfers
> 
> Hi lustre-devel,
> 
> I'd like to gather some opinions about the following question:
> 
> Is it allowed or possible for lustre to submit relatively big bulk
> transfer request (e.g. >512K) to LNET layer when offset in the very
> first page to fetch bulk data from (on sender side) is not equal to the
> offset in the very first page to store data (on receiver side)? In the
> other words - should LNET support such transfers?
> 
> Thanks in advance,
> Maxim
> _______________________________________________
> Lustre-devel mailing list
> Lustre-devel at lists.lustre.org
> http://lists.lustre.org/mailman/listinfo/lustre-devel

[Lustre-devel] lustre-to-LNET API: big non-aligned bulk transfers

[Maxim V. Patlasov]

Eric,

To make things 100% clear - did you answer positively ('It should...') 
because there are some lustre use-cases for such transfers or just 
because it would be natural for LNET to support both aligned and 
not-aligned big bulk transfers?

Thanks in advance,
Maxim

On 10/14/2009 09:22 PM, Eric Barton wrote:
> Maxim,
>
> It should support such transfers, but you have to be careful about
> the number of fragments this can introduce.  This issue has already
> been observed in routers, which buffer LNET message payloads at
> the same page offset, irrespective of the sender's page offset (of
> which it has no knowledge).  For example, this can force the o2iblnd,
> if configured to pre-map all memory, to need double the number of RDMA
> fragments and therefore fail the transfer.  Chat with Liang - he knows
> all about this...
>
>      Cheers,
>                Eric
>
>    
>> -----Original Message-----
>> From: lustre-devel-bounces at lists.lustre.org [mailto:lustre-devel-bounces at lists.lustre.org] On Behalf Of Maxim V.
>> Patlasov
>> Sent: 14 October 2009 8:23 AM
>> To: lustre-devel at lists.lustre.org
>> Subject: [Lustre-devel] lustre-to-LNET API: big non-aligned bulk transfers
>>
>> Hi lustre-devel,
>>
>> I'd like to gather some opinions about the following question:
>>
>> Is it allowed or possible for lustre to submit relatively big bulk
>> transfer request (e.g.>512K) to LNET layer when offset in the very
>> first page to fetch bulk data from (on sender side) is not equal to the
>> offset in the very first page to store data (on receiver side)? In the
>> other words - should LNET support such transfers?
>>
>> Thanks in advance,
>> Maxim
>> _______________________________________________
>> Lustre-devel mailing list
>> Lustre-devel at lists.lustre.org
>> http://lists.lustre.org/mailman/listinfo/lustre-devel
>>      
>
>    

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[Lustre-devel] lustre-to-LNET API: big non-aligned bulk transfers

[jan julian]

Just so your aware, the21057  bugzilla's assignment yesterday was as  
follows.  Who can I get to move this forward so that I can
exchange messages with someone.

People
Reporter:	pravin shelar <pravin.shelar@sun.com>
Assigned To:	pravin shelar <pravin.shelar@sun.com>
Add CC:	
CC:	
Remove selected CCs
On Oct 16, 2009, at 8:49 AM, Maxim V. Patlasov wrote:

> Eric,
>
> To make things 100% clear - did you answer positively ('It  
> should...') because there are some lustre use-cases for such  
> transfers or just because it would be natural for LNET to support  
> both aligned and not-aligned big bulk transfers?
>
> Thanks in advance,
> Maxim
>
> On 10/14/2009 09:22 PM, Eric Barton wrote:
>>
>> Maxim,
>>
>> It should support such transfers, but you have to be careful about
>> the number of fragments this can introduce.  This issue has already
>> been observed in routers, which buffer LNET message payloads at
>> the same page offset, irrespective of the sender's page offset (of
>> which it has no knowledge).  For example, this can force the o2iblnd,
>> if configured to pre-map all memory, to need double the number of  
>> RDMA
>> fragments and therefore fail the transfer.  Chat with Liang - he  
>> knows
>> all about this...
>>
>>     Cheers,
>>               Eric
>>
>>
>>> -----Original Message-----
>>> From: lustre-devel-bounces at lists.lustre.org [mailto:lustre-devel-bounces at lists.lustre.org 
>>> ] On Behalf Of Maxim V.
>>> Patlasov
>>> Sent: 14 October 2009 8:23 AM
>>> To: lustre-devel at lists.lustre.org
>>> Subject: [Lustre-devel] lustre-to-LNET API: big non-aligned bulk  
>>> transfers
>>>
>>> Hi lustre-devel,
>>>
>>> I'd like to gather some opinions about the following question:
>>>
>>> Is it allowed or possible for lustre to submit relatively big bulk
>>> transfer request (e.g. >512K) to LNET layer when offset in the very
>>> first page to fetch bulk data from (on sender side) is not equal  
>>> to the
>>> offset in the very first page to store data (on receiver side)? In  
>>> the
>>> other words - should LNET support such transfers?
>>>
>>> Thanks in advance,
>>> Maxim
>>> _______________________________________________
>>> Lustre-devel mailing list
>>> Lustre-devel at lists.lustre.org
>>> http://lists.lustre.org/mailman/listinfo/lustre-devel
>>>
>>
>>
>
> _______________________________________________
> Lustre-devel mailing list
> Lustre-devel at lists.lustre.org
> http://lists.lustre.org/mailman/listinfo/lustre-devel

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