RE: [PATCH] scsi: storvsc: Fix a panic in the hibernation procedure

[Dexuan Cui]

> From: Ming Lei <ming.lei@xxxxxxxxxx>
> 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