Thread (19 messages) 19 messages, 6 authors, 2022-05-30

Re: vchiq: Performance regression since 5.18-rc1

From: Stefan Wahren <hidden>
Date: 2022-05-25 14:08:38
Also in: linux-mm, lkml, regressions

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:
quoted
On 2022-05-22 01:22:00 [+0200], Stefan Wahren wrote:
quoted
Hi,
Hi,
quoted
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/ (local)

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.

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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