From owner-svn-src-all@FreeBSD.ORG Sat Oct 4 15:59:16 2014 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 955D99A5; Sat, 4 Oct 2014 15:59:16 +0000 (UTC) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:1900:2254:2068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 765D72FA; Sat, 4 Oct 2014 15:59:16 +0000 (UTC) Received: from svn.freebsd.org ([127.0.1.70]) by svn.freebsd.org (8.14.9/8.14.9) with ESMTP id s94FxGlR024430; Sat, 4 Oct 2014 15:59:16 GMT (envelope-from ian@FreeBSD.org) Received: (from ian@localhost) by svn.freebsd.org (8.14.9/8.14.9/Submit) id s94FxGXn024427; Sat, 4 Oct 2014 15:59:16 GMT (envelope-from ian@FreeBSD.org) Message-Id: <201410041559.s94FxGXn024427@svn.freebsd.org> X-Authentication-Warning: svn.freebsd.org: ian set sender to ian@FreeBSD.org using -f From: Ian Lepore Date: Sat, 4 Oct 2014 15:59:16 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r272528 - in head/sys: kern sys X-SVN-Group: head 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: 2.1.18-1 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: Sat, 04 Oct 2014 15:59:16 -0000 Author: ian Date: Sat Oct 4 15:59:15 2014 New Revision: 272528 URL: https://svnweb.freebsd.org/changeset/base/272528 Log: Make kevent(2) periodic timer events more reliably periodic. The event callout is now scheduled using the C_ABSOLUTE flag, and the absolute time of each event is calculated as the time the previous event was scheduled for plus the interval. This ensures that latency in processing a given event doesn't perturb the arrival time of any subsequent events. Reviewed by: jhb Modified: head/sys/kern/kern_event.c head/sys/sys/event.h Modified: head/sys/kern/kern_event.c ============================================================================== --- head/sys/kern/kern_event.c Sat Oct 4 15:42:52 2014 (r272527) +++ head/sys/kern/kern_event.c Sat Oct 4 15:59:15 2014 (r272528) @@ -569,9 +569,10 @@ filt_timerexpire(void *knx) if ((kn->kn_flags & EV_ONESHOT) != EV_ONESHOT) { calloutp = (struct callout *)kn->kn_hook; - callout_reset_sbt_on(calloutp, - timer2sbintime(kn->kn_sdata, kn->kn_sfflags), 0, - filt_timerexpire, kn, PCPU_GET(cpuid), 0); + *kn->kn_ptr.p_nexttime += timer2sbintime(kn->kn_sdata, + kn->kn_sfflags); + callout_reset_sbt_on(calloutp, *kn->kn_ptr.p_nexttime, 0, + filt_timerexpire, kn, PCPU_GET(cpuid), C_ABSOLUTE); } } @@ -607,11 +608,13 @@ filt_timerattach(struct knote *kn) kn->kn_flags |= EV_CLEAR; /* automatically set */ kn->kn_status &= ~KN_DETACHED; /* knlist_add clears it */ + kn->kn_ptr.p_nexttime = malloc(sizeof(sbintime_t), M_KQUEUE, M_WAITOK); calloutp = malloc(sizeof(*calloutp), M_KQUEUE, M_WAITOK); callout_init(calloutp, CALLOUT_MPSAFE); kn->kn_hook = calloutp; - callout_reset_sbt_on(calloutp, to, 0, - filt_timerexpire, kn, PCPU_GET(cpuid), 0); + *kn->kn_ptr.p_nexttime = to + sbinuptime(); + callout_reset_sbt_on(calloutp, *kn->kn_ptr.p_nexttime, 0, + filt_timerexpire, kn, PCPU_GET(cpuid), C_ABSOLUTE); return (0); } @@ -625,6 +628,7 @@ filt_timerdetach(struct knote *kn) calloutp = (struct callout *)kn->kn_hook; callout_drain(calloutp); free(calloutp, M_KQUEUE); + free(kn->kn_ptr.p_nexttime, M_KQUEUE); old = atomic_fetch_sub_explicit(&kq_ncallouts, 1, memory_order_relaxed); KASSERT(old > 0, ("Number of callouts cannot become negative")); kn->kn_status |= KN_DETACHED; /* knlist_remove sets it */ Modified: head/sys/sys/event.h ============================================================================== --- head/sys/sys/event.h Sat Oct 4 15:42:52 2014 (r272527) +++ head/sys/sys/event.h Sat Oct 4 15:59:15 2014 (r272528) @@ -221,6 +221,7 @@ struct knote { struct proc *p_proc; /* proc pointer */ struct aiocblist *p_aio; /* AIO job pointer */ struct aioliojob *p_lio; /* LIO job pointer */ + sbintime_t *p_nexttime; /* next timer event fires at */ void *p_v; /* generic other pointer */ } kn_ptr; struct filterops *kn_fop;