vchiq: Performance regression since 5.18-rc1

[Marcelo Tosatti]

On Wed, May 25, 2022 at 04:07:47PM +0200, Stefan Wahren wrote:
> Hi Marcelo,
> 
> Am 25.05.22 um 15:56 schrieb Marcelo Tosatti:
> > On Mon, May 23, 2022 at 09:09:07AM +0200, Sebastian Andrzej Siewior wrote:
> > > On 2022-05-22 01:22:00 [+0200], Stefan Wahren wrote:
> > > > Hi,
> > > Hi,
> > > 
> > > > while testing the staging/vc04_services/interface/vchiq_arm driver with my
> > > > Raspberry Pi 3 B+ (multi_v7_defconfig) i noticed a huge performance
> > > > regression since [ff042f4a9b050895a42cae893cc01fa2ca81b95c] mm:
> > > > lru_cache_disable: replace work queue synchronization with synchronize_rcu
> > > > 
> > > > Usually i run "vchiq_test -f 1" to see the driver is still working [1].
> > > What about
> > > 	https://lore.kernel.org/all/YmrWK%2FKoU1zrAxPI@fuller.cnet/
> > > 
> > > Sebastian
> > Stefan,
> > 
> > Can you please try the patch above ?
> 
> this was the same as Paul send. I think i need more time for investigation,
> maybe there is an issue with the application.

To clarify: they are not the same patches.

> 
> All i noticed so far is that in good case the CPU usage is around ~ 60 % and
> higher, while in bad case the CPU is almost idle. Also the issue is not
> reproducible with arm64/defconfig.
> 
> > 
> > 
> > 
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> 
>