From owner-svn-src-all@freebsd.org Tue May 22 08:27:34 2018 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 0AE2DEED038; Tue, 22 May 2018 08:27:34 +0000 (UTC) (envelope-from mjg@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id AE6D56988F; Tue, 22 May 2018 08:27:33 +0000 (UTC) (envelope-from mjg@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 8F7E811938; Tue, 22 May 2018 08:27:33 +0000 (UTC) (envelope-from mjg@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id w4M8RXkc051990; Tue, 22 May 2018 08:27:33 GMT (envelope-from mjg@FreeBSD.org) Received: (from mjg@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id w4M8RXeQ051989; Tue, 22 May 2018 08:27:33 GMT (envelope-from mjg@FreeBSD.org) Message-Id: <201805220827.w4M8RXeQ051989@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: mjg set sender to mjg@FreeBSD.org using -f From: Mateusz Guzik Date: Tue, 22 May 2018 08:27:33 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r334026 - head/sys/kern X-SVN-Group: head X-SVN-Commit-Author: mjg X-SVN-Commit-Paths: head/sys/kern X-SVN-Commit-Revision: 334026 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: 2.1.26 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: Tue, 22 May 2018 08:27:34 -0000 Author: mjg Date: Tue May 22 08:27:33 2018 New Revision: 334026 URL: https://svnweb.freebsd.org/changeset/base/334026 Log: Reduce sdt-related branch-fest in mi_switch. The code was evaluating flags before resorting to checking if dtrace is enabled. This was inducing forward jumps in the common case. Modified: head/sys/kern/kern_synch.c Modified: head/sys/kern/kern_synch.c ============================================================================== --- head/sys/kern/kern_synch.c Tue May 22 07:56:58 2018 (r334025) +++ head/sys/kern/kern_synch.c Tue May 22 08:27:33 2018 (r334026) @@ -431,8 +431,9 @@ mi_switch(int flags, struct thread *newtd) CTR4(KTR_PROC, "mi_switch: old thread %ld (td_sched %p, pid %ld, %s)", td->td_tid, td_get_sched(td), td->td_proc->p_pid, td->td_name); #ifdef KDTRACE_HOOKS - if ((flags & SW_PREEMPT) != 0 || ((flags & SW_INVOL) != 0 && - (flags & SW_TYPE_MASK) == SWT_NEEDRESCHED)) + if (__predict_false(sdt_probes_enabled) && + ((flags & SW_PREEMPT) != 0 || ((flags & SW_INVOL) != 0 && + (flags & SW_TYPE_MASK) == SWT_NEEDRESCHED))) SDT_PROBE0(sched, , , preempt); #endif sched_switch(td, newtd, flags);