From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 059FDC25B6B for ; Thu, 26 Oct 2023 11:14:24 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 70EC78D0026; Thu, 26 Oct 2023 07:14:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6BE6A8D0001; Thu, 26 Oct 2023 07:14:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5AD718D0026; Thu, 26 Oct 2023 07:14:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 4D1A88D0001 for ; Thu, 26 Oct 2023 07:14:24 -0400 (EDT) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 22AF4140D5E for ; Thu, 26 Oct 2023 11:14:24 +0000 (UTC) X-FDA: 81387354048.10.C005362 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by imf17.hostedemail.com (Postfix) with ESMTP id 6280E4000F for ; Thu, 26 Oct 2023 11:14:22 +0000 (UTC) Authentication-Results: imf17.hostedemail.com; dkim=none; spf=pass (imf17.hostedemail.com: domain of "SRS0=xBQK=GI=goodmis.org=rostedt@kernel.org" designates 145.40.68.75 as permitted sender) smtp.mailfrom="SRS0=xBQK=GI=goodmis.org=rostedt@kernel.org"; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1698318862; 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=IV2DgnwdRpT62qLzr4XJGTomJVcoxS2E2lAyT5oU7pA=; b=FhQK/jvuV93Kzu3w4PsLnUPPHCX2keTGgsZgrMR2ZiVf3MbDtaSFKJz5T+bEztZkoZ348/ 8oANYy1SKvnV7pXwON7fGtkPYGGdxLC4BQRFC2GwRJStlBMOjRRap1ShD8VUm1aF3p7oKp s3sHcBVNykXwnnKjQg/EV1dzw3TiuwM= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1698318862; a=rsa-sha256; cv=none; b=jReJ+JiLffKlsHRSOIkJzv6suye0VscY+Y5BCW5lDxj7hJpPDZbYBGFtyPLm0ReHk9cBr6 WjLqZwSKWM/mnp23HiqgwlJILYjtAiAOuLggRHXPXjZmBD+elViDR+3HL/tduH/AovpooW ii2cPNC/ww9daFflxYd6F41r7Q9HAns= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=none; spf=pass (imf17.hostedemail.com: domain of "SRS0=xBQK=GI=goodmis.org=rostedt@kernel.org" designates 145.40.68.75 as permitted sender) smtp.mailfrom="SRS0=xBQK=GI=goodmis.org=rostedt@kernel.org"; dmarc=none Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by ams.source.kernel.org (Postfix) with ESMTP id A2E9EB80966; Thu, 26 Oct 2023 11:14:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 438C6C433C7; Thu, 26 Oct 2023 11:14:16 +0000 (UTC) Date: Thu, 26 Oct 2023 07:14:13 -0400 From: Steven Rostedt To: Peter Zijlstra Cc: LKML , Thomas Gleixner , Ankur Arora , Linus Torvalds , 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 , Mathieu Desnoyers Subject: Re: [POC][RFC][PATCH v2] sched: Extended Scheduler Time Slice Message-ID: <20231026071413.4ed47b0e@gandalf.local.home> In-Reply-To: <20231026105944.GJ33965@noisy.programming.kicks-ass.net> References: <20231025235413.597287e1@gandalf.local.home> <20231026105944.GJ33965@noisy.programming.kicks-ass.net> 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-Stat-Signature: iwos43ma6tshyudi7z45bi3qixme6zh6 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 6280E4000F X-Rspam-User: X-HE-Tag: 1698318862-465261 X-HE-Meta: U2FsdGVkX1+NTDDdP8R3aDq1Pzzmbkqzkku8TgMWiM6fkrAzfYMrpaDwIbSgFC1d/IgTmi7pQbK273ArGtw9vkn9J9Vy9b01CZoKNUQUdEdsgKYF8eOn9ju6xnQTsNuUTJF3dWNQdaEPQEepkLvriWygrdARNA6JW0ptrg5AEltcr84BloyVvfHrAlIFmUKSbRGjb3Tbm2LXrUS0OM6NdQwnfFVMeUXo4cFj6wYGud3vtvwUyJYX5iej15QlK/cdLRefQlflkUZPU3GbhwxYcZaJiVjgHf36EyHGJJvH+BcI+pzTDDLpUV+ru1ob9N8uqVoHiHVIGSlVZTW19YrtrIrCMtkqjg8F1zzmFdU5A6h8PAxxO6QP5Ybp+wV1j+jOFFk3wzO7RioS/I4b1OlaBfeepHI54/LrEv+hkOtKldPiNqfCcgEDlJCKRFhXRVk3aifwsiGCbHCif5obbiPK3VSQRkuY+ysCm0J778giEw7eIS6HeD3rADirmJDLhmhLuPZYfl5W3WECNT+aKRx2bzICx7c/dQcpqRq06meXisUfL6lTMbRQ/FPA9a2gI3hbmO9cLZjSwn1d/7Nm0Jwi/E4lzIsI83uLX3SZ7lUP9E/s7njUmaRZ1Hw3Wi8kDk5HE6AEtyHgDfavUlEQvKfdF80FFNLaM7t3gToaQZ5By1npXNK0ho9CNtMZzv/m9BmZC3FBYmsEFZY5Hqh+XJ1xXF7/lTJYGPZVuFBhzSdgBmg1n0GRLCSnDbjH22TYZhxyizF/YazsF36ZJpubf2o0NGn6358YR74Dlso9BNLsyw78HzSTCEl7iCB5ISG5D8A9mbU3loqEIcBe/qxdBj78j/0zZXGUxJT+LVjTOngXLCKZjjgMDZKe8SxoKkMgoJIjBaEDt6ZRfrHu81PU7dddLM9iec0tcALg0nPVCVtu/b/jZ1X5Jj4bt1hRrCWrgI5E0pQntjf76S/3QdCgxAA 9HKStCfM ThHWPm0nm9IGg4dEEKSlxtcRDs9mukqJa3hxuZ4KVQj5a47/bB88IOxi03Z5C/PLtO9tvEiidNa26XJv2aqcSR3bZauLJIhuOYXYU8RSfhapEALSeZBu60hoQv7l8kDFb/17NrE8HaVil4O/qJbkfBsx+9Naob7uFijp8bwpPjcOIwnXNJbf+NXryMoXrfQWMim7VGeFnk5NnJ45za2pWf0cm6ySlgd9n1eY8VjphWC7bp8C8q+PUSM8YvmLwY2p164eClx8hznRZ9iS1UxdWPs2XEdG48G8RdGixSzFKEL83mhSOcfLZpTERqA== 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 12:59:44 +0200 Peter Zijlstra wrote: > On Wed, Oct 25, 2023 at 11:54:13PM -0400, Steven Rostedt wrote: > > > static void extend(void) > > { > > rseq_map.cr_flags = 1; > > } > > > > static void unextend(void) > > { > > unsigned long prev; > > > > prev = xchg(&rseq_map.cr_flags, 0); > > So you complain about overhead and then you add one of the most > expensive ops possible here? xchg has an implicit LOCK prefix and you > really don't need LOCK prefix here. Peter, this is the user space side, where I cut and pasted the code from the file I attached. That has: static inline unsigned long xchg(volatile unsigned *ptr, unsigned new) { unsigned ret = new; asm volatile("xchg %b0,%1" : "+r"(ret), "+m"(*(ptr)) : : "memory"); return ret; } -- Steve > > > if (prev & 2) { > > tracefs_printf(NULL, "Yield!\n"); > > sched_yield(); > > } > > }