From a0842e69aa5f86d61c072544b540ef21b2015211 Mon Sep 17 00:00:00 2001 From: Mateusz Guzik Date: Tue, 18 May 2021 21:07:19 +0200 Subject: [PATCH] lockprof: add contested-only profiling This allows tracking all wait times with much smaller runtime impact. For example when doing -j 104 buildkernel on tmpfs: no profiling: 2921.70s user 282.72s system 6598% cpu 48.562 total all acquires: 2926.87s user 350.53s system 6656% cpu 49.237 total contested only: 2919.64s user 290.31s system 6583% cpu 48.756 total --- sys/kern/subr_lock.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/sys/kern/subr_lock.c b/sys/kern/subr_lock.c index 97b880b54ea2..9c433f683bac 100644 --- a/sys/kern/subr_lock.c +++ b/sys/kern/subr_lock.c @@ -272,6 +272,7 @@ DPCPU_DEFINE_STATIC(struct lock_prof_cpu, lp); #define LP_CPU(cpu) (DPCPU_ID_PTR((cpu), lp)) volatile int __read_mostly lock_prof_enable; +int __read_mostly lock_contested_only; static volatile int lock_prof_resetting; #define LPROF_SBUF_SIZE 256 @@ -605,6 +606,8 @@ lock_profile_obtain_lock_success(struct lock_object *lo, int contested, /* don't reset the timer when/if recursing */ if (!lock_prof_enable || (lo->lo_flags & LO_NOPROFILE)) return; + if (lock_contested_only && !contested) + return; spin = (LOCK_CLASS(lo)->lc_flags & LC_SPINLOCK) ? 1 : 0; if (spin && lock_prof_skipspin == 1) return; @@ -729,6 +732,8 @@ SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipspin, CTLFLAG_RW, &lock_prof_skipspin, 0, "Skip profiling on spinlocks."); SYSCTL_INT(_debug_lock_prof, OID_AUTO, rejected, CTLFLAG_RD, &lock_prof_rejected, 0, "Number of rejected profiling records"); +SYSCTL_INT(_debug_lock_prof, OID_AUTO, contested_only, CTLFLAG_RW, + &lock_contested_only, 0, "Only profile contested acquires"); SYSCTL_PROC(_debug_lock_prof, OID_AUTO, stats, CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, dump_lock_prof_stats, "A",