From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 37614 invoked by alias); 19 Jun 2018 01:26:21 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 37572 invoked by uid 89); 19 Jun 2018 01:26:21 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-25.7 required=5.0 tests=AWL,BAYES_00,GIT_PATCH_0,GIT_PATCH_1,GIT_PATCH_2,GIT_PATCH_3,KAM_SHORT,SPF_PASS autolearn=ham version=3.3.2 spammy=administrator, adaptive, squeeze, trylock X-HELO: mga01.intel.com X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 Subject: Re: [PATCH v4 1/3] Tunables: Add tunables of spin count for pthread adaptive spin mutex To: Adhemerval Zanella , Florian Weimer , Rical Jason , Carlos Donell , Glibc alpha Cc: Dave Hansen , Tim Chen , Andi Kleen , Ying Huang , Aaron Lu , Lu Aubrey References: <1528712339-32299-1-git-send-email-kemi.wang@intel.com> From: kemi Message-ID: <488c18dc-f341-7c7c-ed53-1a7f4ac9d09a@intel.com> Date: Tue, 19 Jun 2018 01:26:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <1528712339-32299-1-git-send-email-kemi.wang@intel.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-SW-Source: 2018-06/txt/msg00532.txt.bz2 PING. Please let me know if anything I need to do here, thanks. https://sourceware.org/ml/libc-alpha/2018-06/msg00178.html https://sourceware.org/ml/libc-alpha/2018-06/msg00179.html https://sourceware.org/ml/libc-alpha/2018-06/msg00180.html Hi, Florian https://sourceware.org/ml/libc-alpha/2018-06/msg00377.html any follow for this thread? On 2018年06月11日 18:18, Kemi Wang wrote: > This patch does not have any functionality change, we only provide a spin > count tunes for pthread adaptive spin mutex. The tunable > glibc.mutex.spin_count tunes can be used by system administrator to squeeze > system performance according to different hardware capabilities and > workload characteristics. > > The maximum value of spin count is limited to 30000 to avoid the overflow > of mutex->__data.__spins variable with the possible type of short in > pthread_mutex_lock (). > > The default value of spin count is set to 100 with the reference to the > previous number of times of spinning via trylock. This value would be > architecture-specific and can be tuned with kinds of benchmarks to fit most > cases in future. > > This is the preparation work for the next patch, in which the way of > adaptive spin would be changed from an expensive cmpxchg to read while > spinning. > > * elf/dl-tunables.list: Add glibc.mutex.spin_count entry. > * manual/tunables.texi: Add glibc.mutex.spin_count description. > * nptl/Makefile: Add pthread_mutex_conf.c for compilation. > * nptl/pthread_mutex_conf.h: New file. > * nptl/pthread_mutex_conf.c: New file. > > ChangeLog: > V3->V4 > a) Add comments in elf/dl-tunables.list > > V2->V3 > a) Polish the description of glibc.mutex.spin_count tunable with the > help from Rical Jasan. > b) Get rid of the TUNABLE_CALLBACK_FNDECL macros in > pthread_mutex_conf.c, as suggested by Florian Weimer. > c) Adjust the default value of spin count to 100 with the reference of > the previous spinning way via trylock. > > V1->V2 > a) Renamed nptl/mutex-conf.h -> nptl/pthread_mutex_conf.h > b) Renamed nptl/mutex-conf.c -> nptl/pthread_mutex_conf.c > c) Change the Makefile to compile pthread_mutex_conf.c > d) Modify the copyright "2013-2018" -> "2018" for new added files > e) Fix the indentation issue (tab -> double space) in > elf/dl-tunables.list > f) Remove the env alias LD_SPIN_COUNT in elf/dl-tunables.list > g) Fix the typo errors and refresh glibc.mutex.spin_count tunable > description in manual/tunables.texi. > h) Fix the indentation issue in nptl/pthread_mutex_conf.c > i) Fix the indentation issue for nested preprocessor (add one space for > each level) > > Suggested-by: Andi Kleen > Signed-off-by: Kemi Wang > --- > elf/dl-tunables.list | 17 +++++++++++ > manual/tunables.texi | 22 ++++++++++++++ > nptl/Makefile | 3 +- > nptl/pthread_mutex_conf.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++ > nptl/pthread_mutex_conf.h | 31 ++++++++++++++++++++ > 5 files changed, 146 insertions(+), 1 deletion(-) > create mode 100644 nptl/pthread_mutex_conf.c > create mode 100644 nptl/pthread_mutex_conf.h > > diff --git a/elf/dl-tunables.list b/elf/dl-tunables.list > index 1f8ecb8..2c5a13f 100644 > --- a/elf/dl-tunables.list > +++ b/elf/dl-tunables.list > @@ -121,4 +121,21 @@ glibc { > default: 3 > } > } > + > +# The maximum value of spin count is limited to 30000 to avoid the overflow > +# of mutex->__data.__spins variable with the possible type of short in > +# pthread_mutex_lock (). > +# > +# The default value of spin count is set to 100 with the reference to the > +# previous number of times of spinning via trylock. This value would be > +# architecture-specific and can be tuned with kinds of benchmarks to fit > +# most cases in future. > + mutex { > + spin_count { > + type: INT_32 > + minval: 0 > + maxval: 30000 > + default: 100 > + } > + } > } > diff --git a/manual/tunables.texi b/manual/tunables.texi > index be33c9f..05c5e4a 100644 > --- a/manual/tunables.texi > +++ b/manual/tunables.texi > @@ -281,6 +281,28 @@ of try lock attempts. > The default value of this tunable is @samp{3}. > @end deftp > > +@node Pthread Mutex Tunables > +@section Pthread Mutex Tunables > +@cindex pthread mutex tunables > + > +@deftp {Tunable namespace} glibc.mutex > +The behavior of pthread mutexes can be tuned to gain performance improvements > +according to specific hardware capabilities and workload characteristics by > +setting the following tunables in the @code{mutex} namespace: > +@end deftp > + > +@deftp Tunable glibc.mutex.spin_count > +The @code{glibc.mutex.spin_count} tunable sets the maximum number of times > +a thread should spin on the lock before calling into the kernel to block. > +Adaptive spin is used for mutexes initialized with the PTHREAD_MUTEX_ADAPTIVE_NP > +GNU extension. It affects both pthread_mutex_lock and pthread_mutex_timedlock. > + > +The spinning is done until either the maximum spin times is reached or > +the lock is acquired. > + > +The default value of this tunable is @samp{100}. > +@end deftp > + > @node Hardware Capability Tunables > @section Hardware Capability Tunables > @cindex hardware capability tunables > diff --git a/nptl/Makefile b/nptl/Makefile > index 94be92c..bd1096f 100644 > --- a/nptl/Makefile > +++ b/nptl/Makefile > @@ -139,7 +139,8 @@ libpthread-routines = nptl-init vars events version pt-interp \ > pthread_mutex_getprioceiling \ > pthread_mutex_setprioceiling \ > pthread_setname pthread_getname \ > - pthread_setattr_default_np pthread_getattr_default_np > + pthread_setattr_default_np pthread_getattr_default_np \ > + pthread_mutex_conf > # pthread_setuid pthread_seteuid pthread_setreuid \ > # pthread_setresuid \ > # pthread_setgid pthread_setegid pthread_setregid \ > diff --git a/nptl/pthread_mutex_conf.c b/nptl/pthread_mutex_conf.c > new file mode 100644 > index 0000000..7f9eb23 > --- /dev/null > +++ b/nptl/pthread_mutex_conf.c > @@ -0,0 +1,74 @@ > +/* pthread_mutex_conf.c: Pthread mutex tunable parameters. > + Copyright (C) 2018 Free Software Foundation, Inc. > + This file is part of the GNU C Library. > + > + The GNU C Library is free software; you can redistribute it and/or > + modify it under the terms of the GNU Lesser General Public > + License as published by the Free Software Foundation; either > + version 2.1 of the License, or (at your option) any later version. > + > + The GNU C Library is distributed in the hope that it will be useful, > + but WITHOUT ANY WARRANTY; without even the implied warranty of > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > + Lesser General Public License for more details. > + > + You should have received a copy of the GNU Lesser General Public > + License along with the GNU C Library; if not, see > + . */ > + > +#include "config.h" > +#include > +#include > +#include > +#include > + > +#if HAVE_TUNABLES > +# define TUNABLE_NAMESPACE mutex > +#endif > +#include > + > + > +struct mutex_config __mutex_aconf = > +{ > + /* The maximum number of times a thread should spin on the lock before > + calling into kernel to block. */ > + .spin_count = 100, > +}; > + > +#if HAVE_TUNABLES > +static inline void __always_inline > +do_set_mutex_spin_count (int32_t value) > +{ > + __mutex_aconf.spin_count = value; > +} > + > +void > +TUNABLE_CALLBACK (set_mutex_spin_count) (tunable_val_t *valp) > +{ > + int32_t value = (int32_t) (valp)->numval; > + do_set_mutex_spin_count (value); > +} > +#endif > + > +static void > +mutex_tunables_init (int argc __attribute__ ((unused)), > + char **argv __attribute__ ((unused)), > + char **environ) > +{ > +#if HAVE_TUNABLES > + TUNABLE_GET (spin_count, int32_t, > + TUNABLE_CALLBACK (set_mutex_spin_count)); > +#endif > +} > + > +#ifdef SHARED > +# define INIT_SECTION ".init_array" > +#else > +# define INIT_SECTION ".preinit_array" > +#endif > + > +void (*const __pthread_mutex_tunables_init_array []) (int, char **, char **) > + __attribute__ ((section (INIT_SECTION), aligned (sizeof (void *)))) = > +{ > + &mutex_tunables_init > +}; > diff --git a/nptl/pthread_mutex_conf.h b/nptl/pthread_mutex_conf.h > new file mode 100644 > index 0000000..e5b027c > --- /dev/null > +++ b/nptl/pthread_mutex_conf.h > @@ -0,0 +1,31 @@ > +/* pthread_mutex_conf.h: Pthread mutex tunable parameters. > + Copyright (C) 2018 Free Software Foundation, Inc. > + This file is part of the GNU C Library. > + > + The GNU C Library is free software; you can redistribute it and/or > + modify it under the terms of the GNU Lesser General Public > + License as published by the Free Software Foundation; either > + version 2.1 of the License, or (at your option) any later version. > + > + The GNU C Library is distributed in the hope that it will be useful, > + but WITHOUT ANY WARRANTY; without even the implied warranty of > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > + Lesser General Public License for more details. > + > + You should have received a copy of the GNU Lesser General Public > + License along with the GNU C Library; if not, see > + . */ > +#ifndef _PTHREAD_MUTEX_CONF_H > +#define _PTHREAD_MUTEX_CONF_H 1 > + > +#include > +#include > + > +struct mutex_config > +{ > + int spin_count; > +}; > + > +extern struct mutex_config __mutex_aconf attribute_hidden; > + > +#endif >