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Make pthread mutexes more scalable

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pthread_mutex_lock() now uses a better algorithm which goes much faster
in multithreaded environments that have lock contention. This comes at
the cost of adding some fixed-cost overhead to mutex invocations. That
doesn't matter for Cosmopolitan because our core libraries all encode
locking operations as NOP instructions when in single-threaded mode.
Overhead only applies starting the moment you first call clone().
This commit is contained in:
Justine Tunney 2022-09-05 13:06:34 -07:00
parent 7de2f229a7
commit 7ff0ea8c13
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GPG key ID: BE714B4575D6E328
32 changed files with 410 additions and 112 deletions
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8
libc/calls/getloadavg-nt.c
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@ -20,7 +20,7 @@
#include "libc/calls/syscall_support-nt.internal.h"
#include "libc/dce.h"
#include "libc/fmt/conv.h"
#include "libc/intrin/spinlock.h"
#include "libc/intrin/pthread.h"
#include "libc/macros.internal.h"
#include "libc/nt/accounting.h"
#include "libc/runtime/sysconf.h"
@ -29,14 +29,14 @@
static int cpus;
static double load;
_Alignas(64) static char lock;
static pthread_spinlock_t lock;
static struct NtFileTime idle1, kern1, user1;
textwindows int sys_getloadavg_nt(double *a, int n) {
int i, rc;
uint64_t elapsed, used;
struct NtFileTime idle, kern, user;
_spinlock(&lock);
pthread_spin_lock(&lock);
if (GetSystemTimes(&idle, &kern, &user)) {
elapsed = (FT(kern) - FT(kern1)) + (FT(user) - FT(user1));
if (elapsed) {
@ -52,7 +52,7 @@ textwindows int sys_getloadavg_nt(double *a, int n) {
} else {
rc = __winerr();
}
_spunlock(&lock);
pthread_spin_unlock(&lock);
return rc;
}