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Wed, 16 Jul 2025 07:54:43 -0700 (PDT) Date: Wed, 16 Jul 2025 10:54:39 -0400 From: Johannes Weiner To: Peter Zijlstra Cc: Beata Michalska , Chris Mason , mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 01/12] sched/psi: Optimize psi_group_change() cpu_clock() usage Message-ID: <20250716145439.GA54289@cmpxchg.org> References: <20250702114924.091581796@infradead.org> <20250702121158.350561696@infradead.org> <0d86c527-27a7-44d5-9ddc-f9a153f67b4d@meta.com> <20250716104050.GR1613200@noisy.programming.kicks-ass.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250716104050.GR1613200@noisy.programming.kicks-ass.net> On Wed, Jul 16, 2025 at 12:40:50PM +0200, Peter Zijlstra wrote: > On Wed, Jul 16, 2025 at 08:53:01AM +0200, Beata Michalska wrote: > > Wouldn't it be enough to use SEQCNT_ZERO? Those are static per-cpu ones. > > Yeah, I suppose that should work. The below builds, but I've not yet > observed the issue myself. > > --- > Subject: sched/psi: Fix psi_seq initialization > From: Peter Zijlstra > Date: Tue, 15 Jul 2025 15:11:14 -0400 > > With the seqcount moved out of the group into a global psi_seq, > re-initializing the seqcount on group creation is causing seqcount > corruption. > > Fixes: 570c8efd5eb7 ("sched/psi: Optimize psi_group_change() cpu_clock() usage") > Reported-by: Chris Mason > Suggested-by: Beata Michalska > Signed-off-by: Peter Zijlstra (Intel) Argh, missed that during the review as well. Acked-by: Johannes Weiner