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Add a knob LIBPTHREAD_BIGSTACK_MAIN, which instructs libthr to leave

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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" <ivan@ivan-labs.com>
Tested by:	dim
Sponsored by:	The FreeBSD Foundation
MFC after:	3 days
This commit is contained in:
Konstantin Belousov 2014-08-13 05:53:41 +00:00
parent f6abec6c64
commit 6c8ce3bfce
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=269909
2 changed files with 12 additions and 1 deletions
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8
lib/libthr/thread/thr_init.c
View File

@ -37,6 +37,7 @@
#include <sys/types.h>
#include <sys/signalvar.h>
#include <sys/ioctl.h>
#include <sys/resource.h>
#include <sys/sysctl.h>
#include <sys/ttycom.h>
#include <sys/mman.h>
@ -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);

5
lib/libthr/thread/thr_stack.c
View File

@ -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;