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Date:   Mon, 23 May 2022 09:09:07 +0200
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From:   Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To:     Stefan Wahren <stefan.wahren@i2se.com>
Cc:     Marcelo Tosatti <mtosatti@redhat.com>,
        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: <YoszE8lQ9VcofLtX@linutronix.de>
References: <77d6d498-7dd9-03eb-60f2-d7e682bb1b20@i2se.com>
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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