Re: [Qemu-devel] [RFC PATCH V5 1/4] colo-compare: introduce colo compare initialization

[Jason Wang <jasowang@redhat.com>]

On 2016年07月08日 16:21, Zhang Chen wrote:
>
>
> On 07/08/2016 11:40 AM, Jason Wang wrote:
>>
>>
>> On 2016年06月23日 19:34, Zhang Chen wrote:
>>> Packets coming from the primary char indev will be sent to outdev
>>> Packets coming from the secondary char dev will be dropped
>>>
>>> usage:
>>>
>>> primary:
>>> -netdev 
>>> tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
>>> -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
>>> -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait
>>> -chardev socket,id=compare1,host=3.3.3.3,port=9004,server,nowait
>>> -chardev socket,id=compare0,host=3.3.3.3,port=9001,server,nowait
>>> -chardev socket,id=compare0-0,host=3.3.3.3,port=9001
>>> -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server,nowait
>>> -chardev socket,id=compare_out0,host=3.3.3.3,port=9005
>>> -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
>>> -object 
>>> filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
>>> -object 
>>> filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
>>> -object 
>>> colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0
>>>
>>> secondary:
>>> -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down 
>>> script=/etc/qemu-ifdown
>>> -device e1000,netdev=hn0,mac=52:a4:00:12:78:66
>>> -chardev socket,id=red0,host=3.3.3.3,port=9003
>>> -chardev socket,id=red1,host=3.3.3.3,port=9004
>>> -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
>>> -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
>>
>> Consider we finally want a non-rfc patch, it's better to have a some 
>> explanations on the above configurations since it was not easy to for 
>> starters at first glance.Maybe you can use either a ascii figure or a 
>> paragraph. Also need to explain the parameter of colo-compare in detail.
>
> Make sense,I will add a ascii figure and some comments to explain it.
>
>>
>>>
>>> Signed-off-by: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
>>> Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
>>> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
>>> ---
>>>   net/Makefile.objs  |   1 +
>>>   net/colo-compare.c | 231 
>>> +++++++++++++++++++++++++++++++++++++++++++++++++++++
>>>   qemu-options.hx    |  34 ++++++++
>>>   vl.c               |   3 +-
>>>   4 files changed, 268 insertions(+), 1 deletion(-)
>>>   create mode 100644 net/colo-compare.c
>>>
>>> diff --git a/net/Makefile.objs b/net/Makefile.objs
>>> index b7c22fd..ba92f73 100644
>>> --- a/net/Makefile.objs
>>> +++ b/net/Makefile.objs
>>> @@ -16,3 +16,4 @@ common-obj-$(CONFIG_NETMAP) += netmap.o
>>>   common-obj-y += filter.o
>>>   common-obj-y += filter-buffer.o
>>>   common-obj-y += filter-mirror.o
>>> +common-obj-y += colo-compare.o
>>> diff --git a/net/colo-compare.c b/net/colo-compare.c
>>> new file mode 100644
>>> index 0000000..a3e1456
>>> --- /dev/null
>>> +++ b/net/colo-compare.c
>>> @@ -0,0 +1,231 @@
>>> +/*
>>> + * COarse-grain LOck-stepping Virtual Machines for Non-stop Service 
>>> (COLO)
>>> + * (a.k.a. Fault Tolerance or Continuous Replication)
>>> + *
>>> + * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
>>> + * Copyright (c) 2016 FUJITSU LIMITED
>>> + * Copyright (c) 2016 Intel Corporation
>>> + *
>>> + * Author: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
>>> + *
>>> + * This work is licensed under the terms of the GNU GPL, version 2 or
>>> + * later.  See the COPYING file in the top-level directory.
>>> + */
>>> +
>>> +#include "qemu/osdep.h"
>>> +#include "qemu/error-report.h"
>>> +#include "qemu-common.h"
>>> +#include "qapi/qmp/qerror.h"
>>> +#include "qapi/error.h"
>>> +#include "net/net.h"
>>> +#include "net/vhost_net.h"
>>> +#include "qom/object_interfaces.h"
>>> +#include "qemu/iov.h"
>>> +#include "qom/object.h"
>>> +#include "qemu/typedefs.h"
>>> +#include "net/queue.h"
>>> +#include "sysemu/char.h"
>>> +#include "qemu/sockets.h"
>>> +#include "qapi-visit.h"
>>> +#include "trace.h"
>>
>> Looks like trace were not really used in the patch, you can delay the 
>> inclusion until is was really used.
>
> OK~~~
>
>>
>>> +
>>> +#define TYPE_COLO_COMPARE "colo-compare"
>>> +#define COLO_COMPARE(obj) \
>>> +    OBJECT_CHECK(CompareState, (obj), TYPE_COLO_COMPARE)
>>> +
>>> +#define COMPARE_READ_LEN_MAX NET_BUFSIZE
>>> +
>>> +static QTAILQ_HEAD(, CompareState) net_compares =
>>> +       QTAILQ_HEAD_INITIALIZER(net_compares);
>>
>> What's the usage of this? A comment would be better.
>
> If we need compare more than one netdev,we should use
> more than one colo-compare. we do checkpoint should flush
> all enqueued packet in colo-compare when work with colo-frame.
> we use this queue to find all colo-compare.
> So, look like no need here, I will move it to after patch.

Yes unless you want a single colo comparing threads to do comparing for 
all netdevs. (But I agree, looks not need).

>
>
>>
>>> +
>>> +typedef struct CompareState {
>>> +    Object parent;
>>> +
>>> +    char *pri_indev;
>>> +    char *sec_indev;
>>> +    char *outdev;
>>> +    CharDriverState *chr_pri_in;
>>> +    CharDriverState *chr_sec_in;
>>> +    CharDriverState *chr_out;
>>> +    QTAILQ_ENTRY(CompareState) next;
>>> +    SocketReadState pri_rs;
>>> +    SocketReadState sec_rs;
>>> +} CompareState;
>>> +
>>> +typedef struct CompareClass {
>>> +    ObjectClass parent_class;
>>> +} CompareClass;
>>> +
>>> +static char *compare_get_pri_indev(Object *obj, Error **errp)
>>> +{
>>> +    CompareState *s = COLO_COMPARE(obj);
>>> +
>>> +    return g_strdup(s->pri_indev);
>>> +}
>>> +
>>> +static void compare_set_pri_indev(Object *obj, const char *value, 
>>> Error **errp)
>>> +{
>>> +    CompareState *s = COLO_COMPARE(obj);
>>> +
>>> +    g_free(s->pri_indev);
>>> +    s->pri_indev = g_strdup(value);
>>
>> I think we need do something more than this, e.g release the orig dev 
>> and get the new one? Or just forbid setting this property.
>>
>
> Do you means that:
> qemu_chr_fe_release(s->chr_pri_in);
>
> If yes,in here we just get/set char* pri_indev(chardev's name).
> We don't get or set CharDriverState, so I think we needn't do more.

Maybe I miss something, but is there any usage for just changing 
chardev's name here?

>
>
>> And looks like we have similar issues for sec_indev and outdev.
>>
>>> +}
>>> +
>>>

[...]

>>> +
>>> +static void colo_compare_finalize(Object *obj)
>>> +{
>>> +    CompareState *s = COLO_COMPARE(obj);
>>> +
>>> +    if (s->chr_pri_in) {
>>> +        qemu_chr_add_handlers(s->chr_pri_in, NULL, NULL, NULL, NULL);
>>
>> Why need do this?
>
> more safty before do qemu_chr_fe_release() for chardev
> like backends/rng-egd.c

Ok, but looks like we don't set any handlers in the patch, so I don't 
get why need to clear it.

For the things of eng-egd, I think we need fail if it was not a socket 
chardev. Vhost-use did similar check in net_vhost_chardev_opts() which 
maybe useful for here (we probably need this for mirror/redirector too).

[...]