Re: Unacceptably Poor RAID1 Performance with Many CPU Cores

[Ali Gholami Rudi <aligrudi@gmail.com>]

On Thu, Jun 15, 2023 at 10:06 PM Yu Kuai <yukuai1@huaweicloud.com> wrote:
> > > FIO configuration file:
> > >
> > > [global]
> > > name=random reads and writes
> > > ioengine=libaio
> > > direct=1
> > > readwrite=randrw
> > > rwmixread=70
> > > iodepth=64
> > > buffered=0
> > > #filename=/dev/ram0
> > > filename=/dev/dm/test
> > > size=1G
> > > runtime=30
> > > time_based
> > > randrepeat=0
> > > norandommap
> > > refill_buffers
> > > ramp_time=10
> > > bs=4k
> > > numjobs=400
> >
> > 400 is too aggressive, I think spin_lock from fast path is probably
> > causing the problem, same as I met before for raid10...

In our workload, we run about this many KVM guests on one machine, and
when many of the VMs use their disks, we experienced almost the same
problem with raid1.

Thanks,
Ali