Date: Wed, 2 Jun 2021 15:15:59 GMT From: Mateusz Guzik <mjg@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: c9f8dcda856c - main - kqueue: replace kq_ncallouts loop with atomic_fetchadd Message-ID: <202106021515.152FFxxi045971@gitrepo.freebsd.org>
next in thread | raw e-mail | index | archive | help
The branch main has been updated by mjg: URL: https://cgit.FreeBSD.org/src/commit/?id=c9f8dcda856c50325190326a618dc251311bc43a commit c9f8dcda856c50325190326a618dc251311bc43a Author: Mateusz Guzik <mjg@FreeBSD.org> AuthorDate: 2021-06-02 15:14:58 +0000 Commit: Mateusz Guzik <mjg@FreeBSD.org> CommitDate: 2021-06-02 15:14:58 +0000 kqueue: replace kq_ncallouts loop with atomic_fetchadd --- sys/kern/kern_event.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/sys/kern/kern_event.c b/sys/kern/kern_event.c index b224ce87087e..63b28cd6024f 100644 --- a/sys/kern/kern_event.c +++ b/sys/kern/kern_event.c @@ -206,7 +206,7 @@ static struct filterops user_filtops = { }; static uma_zone_t knote_zone; -static unsigned int kq_ncallouts = 0; +static unsigned int __exclusive_cache_line kq_ncallouts; static unsigned int kq_calloutmax = 4 * 1024; SYSCTL_UINT(_kern, OID_AUTO, kq_calloutmax, CTLFLAG_RW, &kq_calloutmax, 0, "Maximum number of callouts allocated for kqueue"); @@ -813,18 +813,16 @@ filt_timerattach(struct knote *kn) { struct kq_timer_cb_data *kc; sbintime_t to; - unsigned int ncallouts; int error; error = filt_timervalidate(kn, &to); if (error != 0) return (error); - do { - ncallouts = kq_ncallouts; - if (ncallouts >= kq_calloutmax) - return (ENOMEM); - } while (!atomic_cmpset_int(&kq_ncallouts, ncallouts, ncallouts + 1)); + if (atomic_fetchadd_int(&kq_ncallouts, 1) + 1 > kq_calloutmax) { + atomic_subtract_int(&kq_ncallouts, 1); + return (ENOMEM); + } if ((kn->kn_sfflags & NOTE_ABSTIME) == 0) kn->kn_flags |= EV_CLEAR; /* automatically set */
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?202106021515.152FFxxi045971>