Date: Wed, 29 Mar 2023 12:32:01 +0300 From: Dmitry Chagin <dchagin@freebsd.org> To: Mateusz Guzik <mjg@freebsd.org> Cc: src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Subject: Re: git: 80cf427b8dc1 - main - proc: shave a lock trip on exit if possible Message-ID: <ZCQFkZyexVrPIk3v@heemeyer.club> In-Reply-To: <202303290919.32T9J9Z5085150@gitrepo.freebsd.org> References: <202303290919.32T9J9Z5085150@gitrepo.freebsd.org>
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On Wed, Mar 29, 2023 at 09:19:09AM +0000, Mateusz Guzik wrote: > The branch main has been updated by mjg: > > URL: https://cgit.FreeBSD.org/src/commit/?id=80cf427b8dc18bc5c26fed6d07bc5c5eda4545b0 > > commit 80cf427b8dc18bc5c26fed6d07bc5c5eda4545b0 > Author: Mateusz Guzik <mjg@FreeBSD.org> > AuthorDate: 2023-03-29 08:45:46 +0000 > Commit: Mateusz Guzik <mjg@FreeBSD.org> > CommitDate: 2023-03-29 09:19:03 +0000 > > proc: shave a lock trip on exit if possible > > ... which happens to be vast majority of the time > --- > sys/kern/kern_exit.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/sys/kern/kern_exit.c b/sys/kern/kern_exit.c > index 3f64343aea0e..a92d5cc0f642 100644 > --- a/sys/kern/kern_exit.c > +++ b/sys/kern/kern_exit.c > @@ -477,9 +477,11 @@ exit1(struct thread *td, int rval, int signo) > sx_xunlock(&allproc_lock); > > sx_xlock(&proctree_lock); > - PROC_LOCK(p); > - p->p_flag &= ~(P_TRACED | P_PPWAIT | P_PPTRACE); > - PROC_UNLOCK(p); > + if ((p->p_flag & (P_TRACED | P_PPWAIT | P_PPTRACE)) != 0) { > + PROC_LOCK(p); > + p->p_flag &= ~(P_TRACED | P_PPWAIT | P_PPTRACE); > + PROC_UNLOCK(p); > + } just out of curiosuty, is this can be replaced by a single atomic_clear_rel ? > > /* > * killjobc() might drop and re-acquire proctree_lock to
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