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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-486eb32d3c7sm4672568f8f.10.2026.09.11.03.08.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Sep 2026 03:08:32 -0700 (PDT) Date: Fri, 11 Sep 2026 11:08:31 +0100 From: David Laight To: Haakon Bugge Cc: Waiman Long , Linus Torvalds , Peter Zijlstra , Ingo Molnar , Will Deacon , Boqun Feng , "linux-kernel@vger.kernel.org" , Yafang Shao , Steven Rostedt Subject: Re: [PATCH v4 next 0/9] locking/osq_lock: Optimisations to osq_lock code Message-ID: <20260911110831.5e53cb57@pumpkin> In-Reply-To: References: <20260907084133.3696-1-david.laight.linux@gmail.com> <20260907182705.54585f73@pumpkin> <89F7CD08-2BDD-424D-AA2F-77D72647D93E@oracle.com> <44bdfc4b-4729-4dc3-b7b0-53c671c5ee34@redhat.com> <0ADD6DCD-6EF1-469D-ACB8-EC7D6A94CC2F@oracle.com> <20260910120016.04ba8ae1@pumpkin> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) 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-Transfer-Encoding: 7bit On Thu, 10 Sep 2026 11:31:19 +0000 Haakon Bugge wrote: ... > What concerns me is that I am unable to observe this bug testing > mutexes or rwlocks. That might be because there is only one osq_lock so you always get contention - whereas the other cases have separate locks. You do still need to hit the same array element for it to matter. I'm not sure is makes much sense to have a lot of locks/counters. David