Re: [Xen-devel] xen-blkfront hang

[Dongli Zhang <dongli.zhang@xxxxxxxxxx>]

CCed xen-devel so that more people would be able to help.

Dongli Zhang

On 07/31/2017 09:09 AM, Dongli Zhang wrote:
> Hi Valentin,
> 
> On 07/30/2017 03:42 PM, Valentin Vidic wrote:
>> I'm having a problem with a domU hang in disk IO, described here:
>>
>> https://lists.xen.org/archives/html/xen-users/2017-07/msg00057.html
>>
>> Do you think this is a multi-queue issue and applying one of these
>> latest changes would help?
>>
>> xen/blkfront: always allocate grants first from per-queue persistent grants
>> https://github.com/torvalds/linux/commit/bd912ef3e46b6edb51bb8af4b73fd2be7817e305
> 
> This patch is not able to fix the lack of grant issue permanently. It is used 
> to
> optimize the utilization of grant table entires.
> 
> To verify whether the above patch would help, please check the nr_grant_frames
> value in guest domU. If this value is exactly the same of maximum grant frames
> (by default, xen mainline uses 32) and the number of free grant references is
> very small, the above patch might help.
> 
> The best way is to increase the gnttab_max_frames to larger value (e.g.,  256)
> in dom0 xen.gz grub.
> 
> Dongli Zhang
> 
>>
>> xen-blkfront: fix mq start/stop race
>> https://github.com/torvalds/linux/commit/4b422cb99836de3d261faec20a0329385bdec43d
>>

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