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a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1698349012; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Shf1A3/HUIt2u8uOFJ1YonqbUFaHK5uiEETVGglAeMY=; b=BIjcACVRvMyL/U5sbfxy66Wo44/bXFlgAT3IahLckURAw5usCy+nAnHzAuPB56cGmeJ9+Y vwdx2it3suUgmYdB9rX1m9H73iNE1hDfE5pzmfT/XzoXs87VReIZSVHmaPxIVM9xQwZa2q vndguOpGxMgFOR+Did3mKg1d5Fvz98Y= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id 4B7FECE4285; Thu, 26 Oct 2023 19:36:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id ECBAFC433CA; Thu, 26 Oct 2023 19:36:43 +0000 (UTC) Date: Thu, 26 Oct 2023 15:36:42 -0400 From: Steven Rostedt To: Mathieu Desnoyers 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 Subject: Re: [POC][RFC][PATCH v2] sched: Extended Scheduler Time Slice Message-ID: <20231026153642.06bb418b@gandalf.local.home> In-Reply-To: <7871472b-a0c4-4475-9671-69a3244f956d@efficios.com> 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> X-Mailer: Claws Mail 3.19.1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 3C210C0019 X-Stat-Signature: aqhjzaarrtqzhh6nujmjdo6qf6p64omz X-Rspam-User: X-HE-Tag: 1698349011-15497 X-HE-Meta: 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 rpQAqD+6 Krumom7aOgIqrwwAZvWzb0xNAznOt9mDwgizC6f9CgM94QUhDJEcnvLWajtZI9sLOlBIOE+NeYxvkf4YToXCkHvTPrP536ZwaPekW4zL+oX1SLABdhd1IreFEN3vKb+k2dGVJELk0wIb/IjL6EnD2XAXNJbq597kZx0QEdbdX+s1PPa/asOATljky7NF35gg4zXjyFoSVNN+JGxQB1gIRRzqgtSBFg2O3a1Om34aDKifQpO3MPEeLQZr8g7Si0lWCgN01Kn0Uy0ImNUV5TfOiG1MeMPV3sa9h1CoW/l1golOt5SFBtUNdUWzyew== 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 Thu, 26 Oct 2023 14:59:13 -0400 Mathieu Desnoyers wrote: > > Steven, check out > > > > arch/x86/include/asm/percpu.h > > > > for a rough implementation of a 'xchg()' without SMP coherency, just > > cpu-local one (ie atomic wrt being preempted by the kernel, but not > > atomic wrt other CPU's accessing the same variable concurrently) > > Actually Steven does not need a xchg to test-and-set a single bit which > is only accessed concurrently between kernel and userspace from the same > thread. Either "bts" or "andb" should work fine. Thanks Linus and Mathieu! Yeah, I just changed it to andb and that works just as well (or better). When I first made the change, it became substantially worse. But then I realized it was because I had "addb" and not "andb" :-D -- Steve