linux-kernel - Re: [PATCH v5 00/10] xen-block: multi hardware-queues/rings support

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Date:	Thu, 26 Nov 2015 15:09:02 +0800
From:	Bob Liu <bob.liu@...cle.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC:	xen-devel@...ts.xen.org, linux-kernel@...r.kernel.org,
	roger.pau@...rix.com, felipe.franciosi@...rix.com, axboe@...com,
	avanzini.arianna@...il.com, rafal.mielniczuk@...rix.com,
	jonathan.davies@...rix.com, david.vrabel@...rix.com
Subject: Re: [PATCH v5 00/10] xen-block: multi hardware-queues/rings support


On 11/26/2015 10:57 AM, Konrad Rzeszutek Wilk wrote:
> On Thu, Nov 26, 2015 at 10:28:10AM +0800, Bob Liu wrote:
>>
>> On 11/26/2015 06:12 AM, Konrad Rzeszutek Wilk wrote:
>>> On Wed, Nov 25, 2015 at 03:56:03PM -0500, Konrad Rzeszutek Wilk wrote:
>>>> On Wed, Nov 25, 2015 at 02:25:07PM -0500, Konrad Rzeszutek Wilk wrote:
>>>>>>   xen/blkback: separate ring information out of struct xen_blkif
>>>>>>   xen/blkback: pseudo support for multi hardware queues/rings
>>>>>>   xen/blkback: get the number of hardware queues/rings from blkfront
>>>>>>   xen/blkback: make pool of persistent grants and free pages per-queue
>>>>>
>>>>> OK, got to those as well. I have put them in 'devel/for-jens-4.5' and
>>>>> are going to test them overnight before pushing them out.
>>>>>
>>>>> I see two bugs in the code that we MUST deal with:
>>>>>
>>>>>  - print_stats () is going to show zero values.
>>>>>  - the sysfs code (VBD_SHOW) aren't converted over to fetch data
>>>>>    from all the rings.
>>>>
>>>> - kthread_run can't handle the two "name, i" arguments. I see:
>>>>
>>>> root      5101     2  0 20:47 ?        00:00:00 [blkback.3.xvda-]
>>>> root      5102     2  0 20:47 ?        00:00:00 [blkback.3.xvda-]
>>>
>>> And doing save/restore:
>>>
>>> xl save <id> /tmp/A;
>>> xl restore /tmp/A;
>>>
>>> ends up us loosing the proper state and not getting the ring setup back.
>>> I see this is backend:
>>>
>>> [ 2719.448600] vbd vbd-22-51712: -1 guest requested 0 queues, exceeding the maximum of 3.
>>>
>>> And XenStore agrees:
>>> tool = ""
>>>  xenstored = ""
>>> local = ""
>>>  domain = ""
>>>   0 = ""
>>>    domid = "0"
>>>    name = "Domain-0"
>>>    device-model = ""
>>>     0 = ""
>>>      state = "running"
>>>    error = ""
>>>     backend = ""
>>>      vbd = ""
>>>       2 = ""
>>>        51712 = ""
>>>         error = "-1 guest requested 0 queues, exceeding the maximum of 3."
>>>
>>> .. which also leads to a memory leak as xen_blkbk_remove never gets
>>> called.
>>
>> I think which was already fix by your patch:
>> [PATCH RFC 2/2] xen/blkback: Free resources if connect_ring failed.
> 
> Nope. I get that with or without the patch.
> 

Attached patch should fix this issue. 

-- 
Regards,
-Bob

View attachment "0001-xen-blkfront-fix-compile-error.patch" of type "text/x-patch" (1029 bytes)

View attachment "0002-xen-blkfront-realloc-ring-info-in-blkif_resume.patch" of type "text/x-patch" (1905 bytes)