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Mon, 30 Oct 2023 14:04:46 -0400 (EDT) Message-ID: Date: Mon, 30 Oct 2023 14:05:05 -0400 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [POC][RFC][PATCH v2] sched: Extended Scheduler Time Slice Content-Language: en-US To: Steven Rostedt Cc: Linus Torvalds , Peter Zijlstra , LKML , Thomas Gleixner , Ankur Arora , linux-mm@kvack.org, x86@kernel.org, akpm@linux-foundation.org, luto@kernel.org, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, willy@infradead.org, mgorman@suse.de, jon.grimm@amd.com, bharata@amd.com, raghavendra.kt@amd.com, boris.ostrovsky@oracle.com, konrad.wilk@oracle.com, jgross@suse.com, andrew.cooper3@citrix.com, Joel Fernandes , Youssef Esmat , Vineeth Pillai , Suleiman Souhlal , Ingo Molnar , Daniel Bristot de Oliveira References: <20231025235413.597287e1@gandalf.local.home> <20231026105944.GJ33965@noisy.programming.kicks-ass.net> <20231026071413.4ed47b0e@gandalf.local.home> <7871472b-a0c4-4475-9671-69a3244f956d@efficios.com> <20231026164549.14d45c60@gandalf.local.home> <644da047-2f7a-4d55-a339-f2dc28d2c852@efficios.com> <20231027122442.5c76dd62@gandalf.local.home> <20231027124930.3753cdd4@gandalf.local.home> <20231030094508.031357b4@gandalf.local.home> From: Mathieu Desnoyers In-Reply-To: <20231030094508.031357b4@gandalf.local.home> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: A308840004 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: mf4jz4ocnps6scuxygtonymngn5rmppw X-HE-Tag: 1698689087-85909 X-HE-Meta: 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 +d517aal vULIx9LbdxQJPx91WLleWOfypLY2vO/eEmuJTIkwY2NGxzBmN3QuuxvfJx2obG226oULG1KiGdmd4PRSAWYADST7gdhNTCMvZ1y8OYUzaEYWVNGz7Ma6tiYEBuHHphZdEm+kP0vWrsZH8Iu0frw7CV4OyaLwhKS2L10HHfXTmd+S+7S+jnlEDFRkBfqgONWazddkBP5Vw8rpSo9L5MlLu69yq9VJzF/a/RO/+0NF4KT8TOE5tuT3MG8oU+izMcz1Rji1UtRdXH0HxKvHFeUX4wkpF0xDaTlIv+77RDZnVe0j+z1YiwnmKL74Xv39dJsmLpkK0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2023-10-30 09:45, Steven Rostedt wrote: > On Mon, 30 Oct 2023 08:56:50 -0400 > Mathieu Desnoyers wrote: >> >> This only works if "your" lock implementation is the only user of this >> RSEQ feature within a process. RSEQ requires that multiple libraries can >> share the facilities. Therefore, the rseq field should include the >> nesting counter as part of the RSEQ ABI so various userspace libraries >> can use it collaboratively. >> > > Then I would suggest allowing bit 31 be an "on/off" switch, and the lower > bits to be a counter. When I first tried this with postgres, there was one > lwlock that looked to be held for the majority of the run, so I got rid of > the nesting. But I think a mixture of both would work, where you can have a > nesting counter and an on/off switch with the caveat that if you use it and > enable it, another library may disable it. If you have the nesting counter, why do you need the explicit on/off switch ? Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com