Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Wed, 25 May 2022 12:37:37 -0300
From:   Marcelo Tosatti <mtosatti@redhat.com>
To:     Stefan Wahren <stefan.wahren@i2se.com>
Cc:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Nicolas Saenz Julienne <nsaenzju@redhat.com>,
        Borislav Petkov <bp@alien8.de>,
        Minchan Kim <minchan@kernel.org>,
        Matthew Wilcox <willy@infradead.org>,
        Mel Gorman <mgorman@techsingularity.net>,
        Juri Lelli <juri.lelli@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Phil Elwell <phil@raspberrypi.com>, regressions@lists.linux.dev
Subject: Re: vchiq: Performance regression since 5.18-rc1
Message-ID: <Yo5NQS470wTuDq/f@fuller.cnet>
References: <77d6d498-7dd9-03eb-60f2-d7e682bb1b20@i2se.com>
 <YoszE8lQ9VcofLtX@linutronix.de>
 <Yo41ggMvkI1B9TeM@fuller.cnet>
 <e0402350-687e-14b6-2e30-4b459afa9afb@i2se.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <e0402350-687e-14b6-2e30-4b459afa9afb@i2se.com>
Precedence: bulk

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.
> 
> > 
> > 
> > 
> > _______________________________________________
> > linux-arm-kernel mailing list
> > linux-arm-kernel@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 
>