From dd45734e322a03287d34d8af9b7da7b35cfddb8e Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Mon, 28 Jun 2021 15:48:58 +0200 Subject: [PATCH] nptl: Add glibc.pthread.stack_cache_size tunable The valgrind/helgrind test suite needs a way to make stack dealloction more prompt, and this feature seems to be generally useful. Reviewed-by: Siddhesh Poyarekar --- NEWS | 3 +++ manual/tunables.texi | 9 +++++++++ nptl/nptl-stack.c | 8 ++++---- nptl/nptl-stack.h | 3 +++ nptl/pthread_mutex_conf.c | 9 +++++++++ sysdeps/nptl/dl-tunables.list | 4 ++++ 6 files changed, 32 insertions(+), 4 deletions(-) diff --git a/NEWS b/NEWS index 37ba433..6931135 100644 --- a/NEWS +++ b/NEWS @@ -49,6 +49,9 @@ Major new features: with names ending with .conf to logically classify the converter modules in that directory. +* On Linux, a new tunable, glibc.pthread.stack_cache_size, can be used + to configure the size of the thread stack cache. + Deprecated and removed features, and other changes affecting compatibility: * The function pthread_mutex_consistent_np has been deprecated; programs diff --git a/manual/tunables.texi b/manual/tunables.texi index fe7c131..d5d957f 100644 --- a/manual/tunables.texi +++ b/manual/tunables.texi @@ -402,6 +402,15 @@ is acquired. The default value of this tunable is @samp{100}. @end deftp +@deftp Tunable glibc.pthread.stack_cache_size +This tunable configures the maximum size of the stack cache. Once the +stack cache exceeds this size, unused thread stacks are returned to +the kernel, to bring the cache size below this limit. + +The value is measured in bytes. The default is @samp{41943040} +(fourty mibibytes). +@end deftp + @node Hardware Capability Tunables @section Hardware Capability Tunables @cindex hardware capability tunables diff --git a/nptl/nptl-stack.c b/nptl/nptl-stack.c index 1a0c460..3f33a4c2 100644 --- a/nptl/nptl-stack.c +++ b/nptl/nptl-stack.c @@ -21,8 +21,7 @@ #include #include -/* Maximum size in kB of cache. 40MiBi by default. */ -static const size_t stack_cache_maxsize = 40 * 1024 * 1024; +size_t __nptl_stack_cache_maxsize = 40 * 1024 * 1024; void __nptl_stack_list_del (list_t *elem) @@ -103,8 +102,9 @@ queue_stack (struct pthread *stack) __nptl_stack_list_add (&stack->list, &GL (dl_stack_cache)); GL (dl_stack_cache_actsize) += stack->stackblock_size; - if (__glibc_unlikely (GL (dl_stack_cache_actsize) > stack_cache_maxsize)) - __nptl_free_stacks (stack_cache_maxsize); + if (__glibc_unlikely (GL (dl_stack_cache_actsize) + > __nptl_stack_cache_maxsize)) + __nptl_free_stacks (__nptl_stack_cache_maxsize); } void diff --git a/nptl/nptl-stack.h b/nptl/nptl-stack.h index a6bd8df..8bcfde7 100644 --- a/nptl/nptl-stack.h +++ b/nptl/nptl-stack.h @@ -25,6 +25,9 @@ #include #include +/* Maximum size of the cache, in bytes. 40 MiB by default. */ +extern size_t __nptl_stack_cache_maxsize attribute_hidden; + /* Check whether the stack is still used or not. */ static inline bool __nptl_stack_in_use (struct pthread *pd) diff --git a/nptl/pthread_mutex_conf.c b/nptl/pthread_mutex_conf.c index e6235de..c8f171c 100644 --- a/nptl/pthread_mutex_conf.c +++ b/nptl/pthread_mutex_conf.c @@ -23,6 +23,7 @@ #include #include /* Get STDOUT_FILENO for _dl_printf. */ #include +#include struct mutex_config __mutex_aconf = { @@ -38,10 +39,18 @@ TUNABLE_CALLBACK (set_mutex_spin_count) (tunable_val_t *valp) __mutex_aconf.spin_count = (int32_t) (valp)->numval; } +static void +TUNABLE_CALLBACK (set_stack_cache_size) (tunable_val_t *valp) +{ + __nptl_stack_cache_maxsize = valp->numval; +} + void __pthread_tunables_init (void) { TUNABLE_GET (mutex_spin_count, int32_t, TUNABLE_CALLBACK (set_mutex_spin_count)); + TUNABLE_GET (stack_cache_size, size_t, + TUNABLE_CALLBACK (set_stack_cache_size)); } #endif diff --git a/sysdeps/nptl/dl-tunables.list b/sysdeps/nptl/dl-tunables.list index e3f6432..ac5d053 100644 --- a/sysdeps/nptl/dl-tunables.list +++ b/sysdeps/nptl/dl-tunables.list @@ -23,5 +23,9 @@ glibc { maxval: 32767 default: 100 } + stack_cache_size { + type: SIZE_T + default: 41943040 + } } } -- 2.7.4