From owner-svn-src-all@freebsd.org Thu Sep 26 00:35:07 2019 Return-Path: Delivered-To: svn-src-all@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 6F2EB137260; Thu, 26 Sep 2019 00:35:07 +0000 (UTC) (envelope-from mav@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 46dwtg25P9z4lLW; Thu, 26 Sep 2019 00:35:07 +0000 (UTC) (envelope-from mav@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 256081FF76; Thu, 26 Sep 2019 00:35:07 +0000 (UTC) (envelope-from mav@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id x8Q0Z6m3021658; Thu, 26 Sep 2019 00:35:06 GMT (envelope-from mav@FreeBSD.org) Received: (from mav@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id x8Q0Z6t5021657; Thu, 26 Sep 2019 00:35:06 GMT (envelope-from mav@FreeBSD.org) Message-Id: <201909260035.x8Q0Z6t5021657@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: mav set sender to mav@FreeBSD.org using -f From: Alexander Motin Date: Thu, 26 Sep 2019 00:35:06 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r352728 - head/sys/kern X-SVN-Group: head X-SVN-Commit-Author: mav X-SVN-Commit-Paths: head/sys/kern X-SVN-Commit-Revision: 352728 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 26 Sep 2019 00:35:07 -0000 Author: mav Date: Thu Sep 26 00:35:06 2019 New Revision: 352728 URL: https://svnweb.freebsd.org/changeset/base/352728 Log: Microoptimize sched_pickcpu() CPU affinity on SMT. Use of CPU_FFS() to implement CPUSET_FOREACH() allows to save up to ~0.5% of CPU time on 72-thread SMT system doing 80K IOPS to NVMe from one thread. MFC after: 1 month Sponsored by: iXsystems, Inc. Modified: head/sys/kern/sched_ule.c Modified: head/sys/kern/sched_ule.c ============================================================================== --- head/sys/kern/sched_ule.c Wed Sep 25 22:53:30 2019 (r352727) +++ head/sys/kern/sched_ule.c Thu Sep 26 00:35:06 2019 (r352728) @@ -643,10 +643,6 @@ struct cpu_search { #define CPU_SEARCH_HIGHEST 0x2 #define CPU_SEARCH_BOTH (CPU_SEARCH_LOWEST|CPU_SEARCH_HIGHEST) -#define CPUSET_FOREACH(cpu, mask) \ - for ((cpu) = 0; (cpu) <= mp_maxid; (cpu)++) \ - if (CPU_ISSET(cpu, &mask)) - static __always_inline int cpu_search(const struct cpu_group *cg, struct cpu_search *low, struct cpu_search *high, const int match); int __noinline cpu_search_lowest(const struct cpu_group *cg, @@ -1292,13 +1288,17 @@ sched_pickcpu(struct thread *td, int flags) tdq->tdq_lowpri >= PRI_MIN_IDLE && SCHED_AFFINITY(ts, CG_SHARE_L2)) { if (cg->cg_flags & CG_FLAG_THREAD) { - CPUSET_FOREACH(cpu, cg->cg_mask) { - if (TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE) + /* Check all SMT threads for being idle. */ + for (cpu = CPU_FFS(&cg->cg_mask) - 1; ; cpu++) { + if (CPU_ISSET(cpu, &cg->cg_mask) && + TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE) break; + if (cpu >= mp_maxid) { + SCHED_STAT_INC(pickcpu_idle_affinity); + return (ts->ts_cpu); + } } - } else - cpu = INT_MAX; - if (cpu > mp_maxid) { + } else { SCHED_STAT_INC(pickcpu_idle_affinity); return (ts->ts_cpu); }