From 6c8ce3bfce090eafcf06d293b9deb46f232cea38 Mon Sep 17 00:00:00 2001 From: Konstantin Belousov Date: Wed, 13 Aug 2014 05:53:41 +0000 Subject: [PATCH] Add a knob LIBPTHREAD_BIGSTACK_MAIN, which instructs libthr to leave the whole RLIMIT_STACK-sized region of the kernel-allocated stack as the stack of main thread. By default, the main thread stack is clamped at 2MB (4MB on 64bit ABIs) and the rest is used for other threads stack allocation. Since there is no programmatic way to adjust the size of the main thread stack, pthread_attr_setstacksize() is too late, the knob allows user to manage the main stack size both for single-threaded and multi-threaded processes with the rlimit. Reported by: "Ivan A. Kosarev" Tested by: dim Sponsored by: The FreeBSD Foundation MFC after: 3 days --- lib/libthr/thread/thr_init.c | 8 ++++++++ lib/libthr/thread/thr_stack.c | 5 ++++- 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/lib/libthr/thread/thr_init.c b/lib/libthr/thread/thr_init.c index 937d83f1eb28..9bf0e2955158 100644 --- a/lib/libthr/thread/thr_init.c +++ b/lib/libthr/thread/thr_init.c @@ -37,6 +37,7 @@ #include #include #include +#include #include #include #include @@ -441,6 +442,7 @@ init_main_thread(struct pthread *thread) static void init_private(void) { + struct rlimit rlim; size_t len; int mib[2]; char *env; @@ -471,6 +473,12 @@ init_private(void) len = sizeof (_usrstack); if (sysctl(mib, 2, &_usrstack, &len, NULL, 0) == -1) PANIC("Cannot get kern.usrstack from sysctl"); + env = getenv("LIBPTHREAD_BIGSTACK_MAIN"); + if (env != NULL) { + if (getrlimit(RLIMIT_STACK, &rlim) == -1) + PANIC("Cannot get stack rlimit"); + _thr_stack_initial = rlim.rlim_cur; + } len = sizeof(_thr_is_smp); sysctlbyname("kern.smp.cpus", &_thr_is_smp, &len, NULL, 0); _thr_is_smp = (_thr_is_smp > 1); diff --git a/lib/libthr/thread/thr_stack.c b/lib/libthr/thread/thr_stack.c index 5f8cd4ed2e35..e5d149eedea8 100644 --- a/lib/libthr/thread/thr_stack.c +++ b/lib/libthr/thread/thr_stack.c @@ -246,7 +246,10 @@ _thr_stack_alloc(struct pthread_attr *attr) THREAD_LIST_UNLOCK(curthread); } else { - /* Allocate a stack from usrstack. */ + /* + * Allocate a stack from or below usrstack, depending + * on the LIBPTHREAD_BIGSTACK_MAIN env variable. + */ if (last_stack == NULL) last_stack = _usrstack - _thr_stack_initial - _thr_guard_default;