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SubjectRE: [PATCH] scsi: storvsc: Fix a panic in the hibernation procedure
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> From: Ming Lei <ming.lei@redhat.com>
> Sent: Wednesday, April 22, 2020 2:24 AM
> > ...
> > storvsc_suspend() -> scsi_host_block() is only called in the hibernation
> > path, which is not a hot path at all, so IMHO we don't really care if it
> > takes 10ms or 100ms or even 1s. :-) BTW, in my test, typically the
>
> Are you sure the 'we' can cover all users?

I actully only meant I don't have any performance concern in this path
storvsc_suspend() -> scsi_host_block() :-)

Thanks for your effort to improve the scsi_host_block() API in the patch
[PATCH] scsi: avoid to run synchronize_rcu for each device in scsi_host_block.

> > scsi_host_block() here takes about 3ms in my 40-vCPU VM.
>
> If more LUNs are added, the time should be increased proportionallly,
> that is why I think scsi_host_block() is bad.
>
> Thanks,
> Ming

FWIW, if the time increases linearly against the number of the LUNs, it
looks typically it's still fast enough for storvsc_suspend().

Thanks,
-- Dexuan

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