On 14/12/17(Thu) 16:06, Martin Pieuchot wrote: > Diff below moves amd64 and i386 mutex to the common C implementation. > > The differences are: > - membar_enter_after_atomic(9) instead of membar_enter(9), and > - membar_exit_before_atomic(9) instead of membar_exit(9) > > I'd appreciate any performance test to know if the performance > degradation is acceptable with these barriers.
Hrvoje Popovski confirmed there's not performance regression with this implementation on his forwarding setup. So I'd like reviews and oks before improving stuff in tree. > Index: amd64/amd64/mutex.c > =================================================================== > RCS file: amd64/amd64/mutex.c > diff -N amd64/amd64/mutex.c > --- /dev/null 1 Jan 1970 00:00:00 -0000 > +++ amd64/amd64/mutex.c 14 Dec 2017 14:49:59 -0000 > @@ -0,0 +1,151 @@ > +/* $OpenBSD: mutex.c,v 1.19 2017/09/11 09:52:15 mpi Exp $ */ > + > +/* > + * Copyright (c) 2004 Artur Grabowski <[email protected]> > + * All rights reserved. > + * > + * Redistribution and use in source and binary forms, with or without > + * modification, are permitted provided that the following conditions > + * are met: > + * > + * 1. Redistributions of source code must retain the above copyright > + * notice, this list of conditions and the following disclaimer. > + * 2. The name of the author may not be used to endorse or promote products > + * derived from this software without specific prior written permission. > + * > + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, > + * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY > + * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL > + * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, > + * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, > + * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR > PROFITS; > + * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, > + * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR > + * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF > + * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. > + */ > + > +#include <sys/param.h> > +#include <sys/mutex.h> > +#include <sys/systm.h> > +#include <sys/atomic.h> > + > +#include <machine/intr.h> > + > +#include <ddb/db_output.h> > + > +void > +__mtx_init(struct mutex *mtx, int wantipl) > +{ > + mtx->mtx_owner = NULL; > + mtx->mtx_wantipl = wantipl; > + mtx->mtx_oldipl = IPL_NONE; > +} > + > +#ifdef MULTIPROCESSOR > +#ifdef MP_LOCKDEBUG > +#ifndef DDB > +#error "MP_LOCKDEBUG requires DDB" > +#endif > + > +/* CPU-dependent timing, needs this to be settable from ddb. */ > +extern int __mp_lock_spinout; > +#endif > + > +void > +__mtx_enter(struct mutex *mtx) > +{ > +#ifdef MP_LOCKDEBUG > + int nticks = __mp_lock_spinout; > +#endif > + > + while (__mtx_enter_try(mtx) == 0) { > + CPU_BUSY_CYCLE(); > + > +#ifdef MP_LOCKDEBUG > + if (--nticks == 0) { > + db_printf("%s: %p lock spun out", __func__, mtx); > + db_enter(); > + nticks = __mp_lock_spinout; > + } > +#endif > + } > +} > + > +int > +__mtx_enter_try(struct mutex *mtx) > +{ > + struct cpu_info *owner, *ci = curcpu(); > + int s; > + > + if (mtx->mtx_wantipl != IPL_NONE) > + s = splraise(mtx->mtx_wantipl); > + > + owner = atomic_cas_ptr(&mtx->mtx_owner, NULL, ci); > +#ifdef DIAGNOSTIC > + if (__predict_false(owner == ci)) > + panic("mtx %p: locking against myself", mtx); > +#endif > + if (owner == NULL) { > + membar_enter_after_atomic(); > + if (mtx->mtx_wantipl != IPL_NONE) > + mtx->mtx_oldipl = s; > +#ifdef DIAGNOSTIC > + ci->ci_mutex_level++; > +#endif > + return (1); > + } > + > + if (mtx->mtx_wantipl != IPL_NONE) > + splx(s); > + > + return (0); > +} > +#else > +void > +__mtx_enter(struct mutex *mtx) > +{ > + struct cpu_info *ci = curcpu(); > + > +#ifdef DIAGNOSTIC > + if (__predict_false(mtx->mtx_owner == ci)) > + panic("mtx %p: locking against myself", mtx); > +#endif > + > + if (mtx->mtx_wantipl != IPL_NONE) > + mtx->mtx_oldipl = splraise(mtx->mtx_wantipl); > + > + mtx->mtx_owner = ci; > + > +#ifdef DIAGNOSTIC > + ci->ci_mutex_level++; > +#endif > +} > + > +int > +__mtx_enter_try(struct mutex *mtx) > +{ > + __mtx_enter(mtx); > + return (1); > +} > +#endif > + > +void > +__mtx_leave(struct mutex *mtx) > +{ > + int s; > + > + MUTEX_ASSERT_LOCKED(mtx); > + > +#ifdef DIAGNOSTIC > + curcpu()->ci_mutex_level--; > +#endif > + > + s = mtx->mtx_oldipl; > +#ifdef MULTIPROCESSOR > + membar_exit_before_atomic(); > +#endif > + mtx->mtx_owner = NULL; > + if (mtx->mtx_wantipl != IPL_NONE) > + splx(s); > +} > Index: amd64/conf/files.amd64 > =================================================================== > RCS file: /cvs/src/sys/arch/amd64/conf/files.amd64,v > retrieving revision 1.91 > diff -u -p -r1.91 files.amd64 > --- amd64/conf/files.amd64 17 Oct 2017 14:25:35 -0000 1.91 > +++ amd64/conf/files.amd64 14 Dec 2017 14:51:20 -0000 > @@ -28,7 +28,7 @@ file arch/amd64/amd64/fpu.c > file arch/amd64/amd64/softintr.c > file arch/amd64/amd64/i8259.c > file arch/amd64/amd64/cacheinfo.c > -file arch/amd64/amd64/mutex.S > +file arch/amd64/amd64/mutex.c > file arch/amd64/amd64/vector.S > file arch/amd64/amd64/copy.S > file arch/amd64/amd64/spl.S > Index: i386/conf/files.i386 > =================================================================== > RCS file: /cvs/src/sys/arch/i386/conf/files.i386,v > retrieving revision 1.235 > diff -u -p -r1.235 files.i386 > --- i386/conf/files.i386 17 Oct 2017 14:25:35 -0000 1.235 > +++ i386/conf/files.i386 14 Dec 2017 14:50:43 -0000 > @@ -21,6 +21,7 @@ file arch/i386/i386/est.c !small_kernel > file arch/i386/i386/gdt.c > file arch/i386/i386/in_cksum.s > file arch/i386/i386/machdep.c > +file arch/i386/i386/mutex.c > file arch/i386/i386/hibernate_machdep.c hibernate > file arch/i386/i386/via.c > file arch/i386/i386/locore.s > Index: i386/i386/locore.s > =================================================================== > RCS file: /cvs/src/sys/arch/i386/i386/locore.s,v > retrieving revision 1.180 > diff -u -p -r1.180 locore.s > --- i386/i386/locore.s 25 Aug 2017 19:28:48 -0000 1.180 > +++ i386/i386/locore.s 14 Dec 2017 14:45:36 -0000 > @@ -1319,8 +1319,6 @@ ENTRY(cpu_paenable) > #include <i386/i386/apicvec.s> > #endif > > -#include <i386/i386/mutex.S> > - > .section .rodata > .globl _C_LABEL(_stac) > _C_LABEL(_stac): > Index: i386/i386/mutex.c > =================================================================== > RCS file: i386/i386/mutex.c > diff -N i386/i386/mutex.c > --- /dev/null 1 Jan 1970 00:00:00 -0000 > +++ i386/i386/mutex.c 14 Dec 2017 14:47:29 -0000 > @@ -0,0 +1,151 @@ > +/* $OpenBSD: mutex.c,v 1.19 2017/09/11 09:52:15 mpi Exp $ */ > + > +/* > + * Copyright (c) 2004 Artur Grabowski <[email protected]> > + * All rights reserved. > + * > + * Redistribution and use in source and binary forms, with or without > + * modification, are permitted provided that the following conditions > + * are met: > + * > + * 1. Redistributions of source code must retain the above copyright > + * notice, this list of conditions and the following disclaimer. > + * 2. The name of the author may not be used to endorse or promote products > + * derived from this software without specific prior written permission. > + * > + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, > + * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY > + * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL > + * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, > + * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, > + * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR > PROFITS; > + * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, > + * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR > + * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF > + * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. > + */ > + > +#include <sys/param.h> > +#include <sys/mutex.h> > +#include <sys/systm.h> > +#include <sys/atomic.h> > + > +#include <machine/intr.h> > + > +#include <ddb/db_output.h> > + > +void > +__mtx_init(struct mutex *mtx, int wantipl) > +{ > + mtx->mtx_owner = NULL; > + mtx->mtx_wantipl = wantipl; > + mtx->mtx_oldipl = IPL_NONE; > +} > + > +#ifdef MULTIPROCESSOR > +#ifdef MP_LOCKDEBUG > +#ifndef DDB > +#error "MP_LOCKDEBUG requires DDB" > +#endif > + > +/* CPU-dependent timing, needs this to be settable from ddb. */ > +extern int __mp_lock_spinout; > +#endif > + > +void > +__mtx_enter(struct mutex *mtx) > +{ > +#ifdef MP_LOCKDEBUG > + int nticks = __mp_lock_spinout; > +#endif > + > + while (__mtx_enter_try(mtx) == 0) { > + CPU_BUSY_CYCLE(); > + > +#ifdef MP_LOCKDEBUG > + if (--nticks == 0) { > + db_printf("%s: %p lock spun out", __func__, mtx); > + db_enter(); > + nticks = __mp_lock_spinout; > + } > +#endif > + } > +} > + > +int > +__mtx_enter_try(struct mutex *mtx) > +{ > + struct cpu_info *owner, *ci = curcpu(); > + int s; > + > + if (mtx->mtx_wantipl != IPL_NONE) > + s = splraise(mtx->mtx_wantipl); > + > + owner = atomic_cas_ptr(&mtx->mtx_owner, NULL, ci); > +#ifdef DIAGNOSTIC > + if (__predict_false(owner == ci)) > + panic("mtx %p: locking against myself", mtx); > +#endif > + if (owner == NULL) { > + membar_enter_after_atomic(); > + if (mtx->mtx_wantipl != IPL_NONE) > + mtx->mtx_oldipl = s; > +#ifdef DIAGNOSTIC > + ci->ci_mutex_level++; > +#endif > + return (1); > + } > + > + if (mtx->mtx_wantipl != IPL_NONE) > + splx(s); > + > + return (0); > +} > +#else > +void > +__mtx_enter(struct mutex *mtx) > +{ > + struct cpu_info *ci = curcpu(); > + > +#ifdef DIAGNOSTIC > + if (__predict_false(mtx->mtx_owner == ci)) > + panic("mtx %p: locking against myself", mtx); > +#endif > + > + if (mtx->mtx_wantipl != IPL_NONE) > + mtx->mtx_oldipl = splraise(mtx->mtx_wantipl); > + > + mtx->mtx_owner = ci; > + > +#ifdef DIAGNOSTIC > + ci->ci_mutex_level++; > +#endif > +} > + > +int > +__mtx_enter_try(struct mutex *mtx) > +{ > + __mtx_enter(mtx); > + return (1); > +} > +#endif > + > +void > +__mtx_leave(struct mutex *mtx) > +{ > + int s; > + > + MUTEX_ASSERT_LOCKED(mtx); > + > +#ifdef DIAGNOSTIC > + curcpu()->ci_mutex_level--; > +#endif > + > + s = mtx->mtx_oldipl; > +#ifdef MULTIPROCESSOR > + membar_exit_before_atomic(); > +#endif > + mtx->mtx_owner = NULL; > + if (mtx->mtx_wantipl != IPL_NONE) > + splx(s); > +} >
