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

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Date:	Thu, 26 Nov 2015 10:28:10 +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 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.

P.S. I didn't see your git tree updated with these patches.

-- 
Regards,
-Bob
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