Date: Sat, 17 Feb 2018 00:23:28 +0000 (UTC) From: Mateusz Guzik <mjg@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r329420 - head/sys/kern Message-ID: <201802170023.w1H0NSH0030381@repo.freebsd.org>
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Author: mjg Date: Sat Feb 17 00:23:28 2018 New Revision: 329420 URL: https://svnweb.freebsd.org/changeset/base/329420 Log: Postpone sx_sunlock(&proctree_lock) on fork until after allproc is dropped. There is a significant contention on the lock during -j 128 package build. This change drops total wait time on this lock by 60%. Modified: head/sys/kern/kern_fork.c Modified: head/sys/kern/kern_fork.c ============================================================================== --- head/sys/kern/kern_fork.c Sat Feb 17 00:21:50 2018 (r329419) +++ head/sys/kern/kern_fork.c Sat Feb 17 00:23:28 2018 (r329420) @@ -401,8 +401,6 @@ do_fork(struct thread *td, struct fork_req *fr, struct trypid = fork_findpid(fr->fr_flags); - sx_sunlock(&proctree_lock); - p2->p_state = PRS_NEW; /* protect against others */ p2->p_pid = trypid; AUDIT_ARG_PID(p2->p_pid); @@ -414,6 +412,7 @@ do_fork(struct thread *td, struct fork_req *fr, struct PROC_LOCK(p1); sx_xunlock(&allproc_lock); + sx_sunlock(&proctree_lock); bcopy(&p1->p_startcopy, &p2->p_startcopy, __rangeof(struct proc, p_startcopy, p_endcopy)); @@ -977,8 +976,8 @@ fork1(struct thread *td, struct fork_req *fr) } error = EAGAIN; - sx_sunlock(&proctree_lock); sx_xunlock(&allproc_lock); + sx_sunlock(&proctree_lock); #ifdef MAC mac_proc_destroy(newproc); #endif
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