Date: Fri, 17 Nov 2017 20:41:18 +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: r325958 - in head: share/man/man9 sys/conf sys/kern Message-ID: <201711172041.vAHKfImC006244@repo.freebsd.org>
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Author: mjg Date: Fri Nov 17 20:41:17 2017 New Revision: 325958 URL: https://svnweb.freebsd.org/changeset/base/325958 Log: lockmgr: remove the ADAPTIVE_LOCKMGRS option The code was never enabled and is very heavy weight. A revamped adaptive spinning may show up at a later time. Discussed with: kib Modified: head/share/man/man9/lock.9 head/sys/conf/options head/sys/kern/kern_lock.c Modified: head/share/man/man9/lock.9 ============================================================================== --- head/share/man/man9/lock.9 Fri Nov 17 19:25:39 2017 (r325957) +++ head/share/man/man9/lock.9 Fri Nov 17 20:41:17 2017 (r325958) @@ -26,7 +26,7 @@ .\" .\" $FreeBSD$ .\" -.Dd November 2, 2014 +.Dd November 17, 2017 .Dt LOCK 9 .Os .Sh NAME @@ -93,9 +93,6 @@ The timeout value passed to .It Fa flags The flags the lock is to be initialized with: .Bl -tag -width ".Dv LK_CANRECURSE" -.It Dv LK_ADAPTIVE -Enable adaptive spinning for this lock if the kernel is compiled with the -ADAPTIVE_LOCKMGRS option. .It Dv LK_CANRECURSE Allow recursive exclusive locks. .It Dv LK_NOPROFILE Modified: head/sys/conf/options ============================================================================== --- head/sys/conf/options Fri Nov 17 19:25:39 2017 (r325957) +++ head/sys/conf/options Fri Nov 17 20:41:17 2017 (r325958) @@ -69,7 +69,6 @@ TEXTDUMP_VERBOSE opt_ddb.h NUM_CORE_FILES opt_global.h # Miscellaneous options. -ADAPTIVE_LOCKMGRS ALQ ALTERA_SDCARD_FAST_SIM opt_altera_sdcard.h ATSE_CFI_HACK opt_cfi.h Modified: head/sys/kern/kern_lock.c ============================================================================== --- head/sys/kern/kern_lock.c Fri Nov 17 19:25:39 2017 (r325957) +++ head/sys/kern/kern_lock.c Fri Nov 17 20:41:17 2017 (r325958) @@ -26,7 +26,6 @@ * DAMAGE. */ -#include "opt_adaptive_lockmgrs.h" #include "opt_ddb.h" #include "opt_hwpmc_hooks.h" @@ -159,15 +158,6 @@ struct lock_class lock_class_lockmgr = { #endif }; -#ifdef ADAPTIVE_LOCKMGRS -static u_int alk_retries = 10; -static u_int alk_loops = 10000; -static SYSCTL_NODE(_debug, OID_AUTO, lockmgr, CTLFLAG_RD, NULL, - "lockmgr debugging"); -SYSCTL_UINT(_debug_lockmgr, OID_AUTO, retries, CTLFLAG_RW, &alk_retries, 0, ""); -SYSCTL_UINT(_debug_lockmgr, OID_AUTO, loops, CTLFLAG_RW, &alk_loops, 0, ""); -#endif - static bool __always_inline lockmgr_slock_try(struct lock *lk, uintptr_t *xp, int flags); static bool __always_inline lockmgr_sunlock_try(struct lock *lk, uintptr_t x); @@ -661,10 +651,6 @@ __lockmgr_args(struct lock *lk, u_int flags, struct lo uint64_t waittime = 0; int contested = 0; #endif -#ifdef ADAPTIVE_LOCKMGRS - volatile struct thread *owner; - u_int i, spintries = 0; -#endif error = 0; tid = (uintptr_t)curthread; @@ -748,76 +734,7 @@ __lockmgr_args(struct lock *lk, u_int flags, struct lo break; } -#ifdef ADAPTIVE_LOCKMGRS /* - * If the owner is running on another CPU, spin until - * the owner stops running or the state of the lock - * changes. We need a double-state handle here - * because for a failed acquisition the lock can be - * either held in exclusive mode or shared mode - * (for the writer starvation avoidance technique). - */ - if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 && - LK_HOLDER(x) != LK_KERNPROC) { - owner = (struct thread *)LK_HOLDER(x); - if (LOCK_LOG_TEST(&lk->lock_object, 0)) - CTR3(KTR_LOCK, - "%s: spinning on %p held by %p", - __func__, lk, owner); - KTR_STATE1(KTR_SCHED, "thread", - sched_tdname(td), "spinning", - "lockname:\"%s\"", lk->lock_object.lo_name); - - /* - * If we are holding also an interlock drop it - * in order to avoid a deadlock if the lockmgr - * owner is adaptively spinning on the - * interlock itself. - */ - if (flags & LK_INTERLOCK) { - class->lc_unlock(ilk); - flags &= ~LK_INTERLOCK; - } - GIANT_SAVE(); - while (LK_HOLDER(lk->lk_lock) == - (uintptr_t)owner && TD_IS_RUNNING(owner)) - cpu_spinwait(); - KTR_STATE0(KTR_SCHED, "thread", - sched_tdname(td), "running"); - GIANT_RESTORE(); - continue; - } else if (LK_CAN_ADAPT(lk, flags) && - (x & LK_SHARE) != 0 && LK_SHARERS(x) && - spintries < alk_retries) { - KTR_STATE1(KTR_SCHED, "thread", - sched_tdname(td), "spinning", - "lockname:\"%s\"", lk->lock_object.lo_name); - if (flags & LK_INTERLOCK) { - class->lc_unlock(ilk); - flags &= ~LK_INTERLOCK; - } - GIANT_SAVE(); - spintries++; - for (i = 0; i < alk_loops; i++) { - if (LOCK_LOG_TEST(&lk->lock_object, 0)) - CTR4(KTR_LOCK, - "%s: shared spinning on %p with %u and %u", - __func__, lk, spintries, i); - x = lk->lk_lock; - if ((x & LK_SHARE) == 0 || - LK_CAN_SHARE(x, flags) != 0) - break; - cpu_spinwait(); - } - KTR_STATE0(KTR_SCHED, "thread", - sched_tdname(td), "running"); - GIANT_RESTORE(); - if (i != alk_loops) - continue; - } -#endif - - /* * Acquire the sleepqueue chain lock because we * probabilly will need to manipulate waiters flags. */ @@ -833,25 +750,7 @@ __lockmgr_args(struct lock *lk, u_int flags, struct lo continue; } -#ifdef ADAPTIVE_LOCKMGRS /* - * The current lock owner might have started executing - * on another CPU (or the lock could have changed - * owner) while we were waiting on the turnstile - * chain lock. If so, drop the turnstile lock and try - * again. - */ - if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 && - LK_HOLDER(x) != LK_KERNPROC) { - owner = (struct thread *)LK_HOLDER(x); - if (TD_IS_RUNNING(owner)) { - sleepq_release(&lk->lock_object); - continue; - } - } -#endif - - /* * Try to set the LK_SHARED_WAITERS flag. If we fail, * loop back and retry. */ @@ -992,77 +891,7 @@ __lockmgr_args(struct lock *lk, u_int flags, struct lo break; } -#ifdef ADAPTIVE_LOCKMGRS /* - * If the owner is running on another CPU, spin until - * the owner stops running or the state of the lock - * changes. - */ - x = lk->lk_lock; - if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 && - LK_HOLDER(x) != LK_KERNPROC) { - owner = (struct thread *)LK_HOLDER(x); - if (LOCK_LOG_TEST(&lk->lock_object, 0)) - CTR3(KTR_LOCK, - "%s: spinning on %p held by %p", - __func__, lk, owner); - KTR_STATE1(KTR_SCHED, "thread", - sched_tdname(td), "spinning", - "lockname:\"%s\"", lk->lock_object.lo_name); - - /* - * If we are holding also an interlock drop it - * in order to avoid a deadlock if the lockmgr - * owner is adaptively spinning on the - * interlock itself. - */ - if (flags & LK_INTERLOCK) { - class->lc_unlock(ilk); - flags &= ~LK_INTERLOCK; - } - GIANT_SAVE(); - while (LK_HOLDER(lk->lk_lock) == - (uintptr_t)owner && TD_IS_RUNNING(owner)) - cpu_spinwait(); - KTR_STATE0(KTR_SCHED, "thread", - sched_tdname(td), "running"); - GIANT_RESTORE(); - continue; - } else if (LK_CAN_ADAPT(lk, flags) && - (x & LK_SHARE) != 0 && LK_SHARERS(x) && - spintries < alk_retries) { - if ((x & LK_EXCLUSIVE_SPINNERS) == 0 && - !atomic_cmpset_ptr(&lk->lk_lock, x, - x | LK_EXCLUSIVE_SPINNERS)) - continue; - KTR_STATE1(KTR_SCHED, "thread", - sched_tdname(td), "spinning", - "lockname:\"%s\"", lk->lock_object.lo_name); - if (flags & LK_INTERLOCK) { - class->lc_unlock(ilk); - flags &= ~LK_INTERLOCK; - } - GIANT_SAVE(); - spintries++; - for (i = 0; i < alk_loops; i++) { - if (LOCK_LOG_TEST(&lk->lock_object, 0)) - CTR4(KTR_LOCK, - "%s: shared spinning on %p with %u and %u", - __func__, lk, spintries, i); - if ((lk->lk_lock & - LK_EXCLUSIVE_SPINNERS) == 0) - break; - cpu_spinwait(); - } - KTR_STATE0(KTR_SCHED, "thread", - sched_tdname(td), "running"); - GIANT_RESTORE(); - if (i != alk_loops) - continue; - } -#endif - - /* * Acquire the sleepqueue chain lock because we * probabilly will need to manipulate waiters flags. */ @@ -1077,24 +906,6 @@ __lockmgr_args(struct lock *lk, u_int flags, struct lo sleepq_release(&lk->lock_object); continue; } - -#ifdef ADAPTIVE_LOCKMGRS - /* - * The current lock owner might have started executing - * on another CPU (or the lock could have changed - * owner) while we were waiting on the turnstile - * chain lock. If so, drop the turnstile lock and try - * again. - */ - if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 && - LK_HOLDER(x) != LK_KERNPROC) { - owner = (struct thread *)LK_HOLDER(x); - if (TD_IS_RUNNING(owner)) { - sleepq_release(&lk->lock_object); - continue; - } - } -#endif /* * The lock can be in the state where there is a
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