On Wed, Dec 19, 2018 at 10:52:03AM +0100, Otto Moerbeek wrote:
> Hi,
>
> This diff implements a more flexible approach for the number of pools
> malloc uses in the multi-threaded case. At the momemt I do not intend
> to commit this as-is, I first need this to get some feedback on what
> the proper default should be.
>
> Currently the number of pools is fixed at 4. More pools mean less
> contention for allocations, but free becomes more expensive since a
> thread might need to check other pools increasing contention.
>
> I'd like to know how this diff behaves using your favorite
> mutli-threaded application. Often this will be a web-browser I guess.
>
> Test instructions:
>
> 0. Make sure you are running current.
>
> 1. Do a baseline test of your application.
>
> 2. Apply diff, build and install userland.
>
> 3. Run your test application with MALLOC_OPTIONS=value, where value is:
> "", +, -, ++, -- and +++.
>
> e.g.
>
> MALLOC_OPTIONS=++ chrome
>
> Note performance. Do multiple tests to get better statistics.
>
> If you're not able to do full tests, at least general observations are
> welcome. Tell a bit about the system you tested on (e.g. number of
> cores). Note that due to randomization, different runs might show
> different performance numbers since the pools shared by subsets of
> threads can turn out differently.
>
> Thanks,
>
> -Otto
New diff with problem noted by Janne Johansson fixed.
Index: include/thread_private.h
===================================================================
RCS file: /cvs/src/lib/libc/include/thread_private.h,v
retrieving revision 1.33
diff -u -p -r1.33 thread_private.h
--- include/thread_private.h 5 Dec 2017 13:45:31 -0000 1.33
+++ include/thread_private.h 19 Dec 2018 10:18:38 -0000
@@ -7,7 +7,7 @@
#include <stdio.h> /* for FILE and __isthreaded */
-#define _MALLOC_MUTEXES 4
+#define _MALLOC_MUTEXES 32
void _malloc_init(int);
#ifdef __LIBC__
PROTO_NORMAL(_malloc_init);
Index: stdlib/malloc.c
===================================================================
RCS file: /cvs/src/lib/libc/stdlib/malloc.c,v
retrieving revision 1.257
diff -u -p -r1.257 malloc.c
--- stdlib/malloc.c 10 Dec 2018 07:57:49 -0000 1.257
+++ stdlib/malloc.c 19 Dec 2018 10:18:38 -0000
@@ -143,6 +143,8 @@ struct dir_info {
size_t cheap_reallocs;
size_t malloc_used; /* bytes allocated */
size_t malloc_guarded; /* bytes used for guards */
+ size_t pool_searches; /* searches for pool */
+ size_t other_pool; /* searches in other pool */
#define STATS_ADD(x,y) ((x) += (y))
#define STATS_SUB(x,y) ((x) -= (y))
#define STATS_INC(x) ((x)++)
@@ -179,7 +181,9 @@ struct chunk_info {
};
struct malloc_readonly {
- struct dir_info *malloc_pool[_MALLOC_MUTEXES]; /* Main bookkeeping
information */
+ /* Main bookkeeping information */
+ struct dir_info *malloc_pool[_MALLOC_MUTEXES];
+ u_int malloc_mutexes; /* how much in actual use? */
int malloc_mt; /* multi-threaded mode? */
int malloc_freecheck; /* Extensive double free check */
int malloc_freeunmap; /* mprotect free pages PROT_NONE? */
@@ -267,7 +271,7 @@ getpool(void)
return mopts.malloc_pool[0];
else
return mopts.malloc_pool[TIB_GET()->tib_tid &
- (_MALLOC_MUTEXES - 1)];
+ (mopts.malloc_mutexes - 1)];
}
static __dead void
@@ -316,6 +320,16 @@ static void
omalloc_parseopt(char opt)
{
switch (opt) {
+ case '+':
+ mopts.malloc_mutexes <<= 1;
+ if (mopts.malloc_mutexes > _MALLOC_MUTEXES)
+ mopts.malloc_mutexes = _MALLOC_MUTEXES;
+ break;
+ case '-':
+ mopts.malloc_mutexes >>= 1;
+ if (mopts.malloc_mutexes < 1)
+ mopts.malloc_mutexes = 1;
+ break;
case '>':
mopts.malloc_cache <<= 1;
if (mopts.malloc_cache > MALLOC_MAXCACHE)
@@ -395,6 +409,7 @@ omalloc_init(void)
/*
* Default options
*/
+ mopts.malloc_mutexes = 4;
mopts.malloc_junk = 1;
mopts.malloc_cache = MALLOC_DEFAULT_CACHE;
@@ -485,7 +500,7 @@ omalloc_poolinit(struct dir_info **dp)
for (j = 0; j < MALLOC_CHUNK_LISTS; j++)
LIST_INIT(&d->chunk_dir[i][j]);
}
- STATS_ADD(d->malloc_used, regioninfo_size);
+ STATS_ADD(d->malloc_used, regioninfo_size + 3 * MALLOC_PAGESIZE);
d->canary1 = mopts.malloc_canary ^ (u_int32_t)(uintptr_t)d;
d->canary2 = ~d->canary1;
@@ -1196,7 +1211,7 @@ _malloc_init(int from_rthreads)
if (!mopts.malloc_canary)
omalloc_init();
- max = from_rthreads ? _MALLOC_MUTEXES : 1;
+ max = from_rthreads ? mopts.malloc_mutexes : 1;
if (((uintptr_t)&malloc_readonly & MALLOC_PAGEMASK) == 0)
mprotect(&malloc_readonly, sizeof(malloc_readonly),
PROT_READ | PROT_WRITE);
@@ -1281,16 +1296,19 @@ findpool(void *p, struct dir_info *argpo
struct dir_info *pool = argpool;
struct region_info *r = find(pool, p);
+ STATS_INC(pool->pool_searches);
if (r == NULL) {
if (mopts.malloc_mt) {
int i;
- for (i = 0; i < _MALLOC_MUTEXES; i++) {
- if (i == argpool->mutex)
- continue;
+ STATS_INC(pool->other_pool);
+ for (i = 1; i < mopts.malloc_mutexes; i++) {
+ int j = (argpool->mutex + i) &
+ (mopts.malloc_mutexes - 1);
+
pool->active--;
_MALLOC_UNLOCK(pool->mutex);
- pool = mopts.malloc_pool[i];
+ pool = mopts.malloc_pool[j];
_MALLOC_LOCK(pool->mutex);
pool->active++;
r = find(pool, p);
@@ -2220,14 +2238,13 @@ malloc_dump1(int fd, int poolno, struct
return;
dprintf(fd, "Region slots free %zu/%zu\n",
d->regions_free, d->regions_total);
- dprintf(fd, "Finds %zu/%zu\n", d->finds,
- d->find_collisions);
- dprintf(fd, "Inserts %zu/%zu\n", d->inserts,
- d->insert_collisions);
- dprintf(fd, "Deletes %zu/%zu\n", d->deletes,
- d->delete_moves);
+ dprintf(fd, "Finds %zu/%zu\n", d->finds, d->find_collisions);
+ dprintf(fd, "Inserts %zu/%zu\n", d->inserts, d->insert_collisions);
+ dprintf(fd, "Deletes %zu/%zu\n", d->deletes, d->delete_moves);
dprintf(fd, "Cheap reallocs %zu/%zu\n",
d->cheap_reallocs, d->cheap_realloc_tries);
+ dprintf(fd, "Other pool searches %zu/%zu\n",
+ d->other_pool, d->pool_searches);
dprintf(fd, "In use %zu\n", d->malloc_used);
dprintf(fd, "Guarded %zu\n", d->malloc_guarded);
dump_free_chunk_info(fd, d);
@@ -2289,7 +2306,7 @@ malloc_gdump(int fd)
int i;
int saved_errno = errno;
- for (i = 0; i < _MALLOC_MUTEXES; i++)
+ for (i = 0; i < mopts.malloc_mutexes; i++)
malloc_dump(fd, i, mopts.malloc_pool[i]);
errno = saved_errno;
@@ -2305,15 +2322,15 @@ malloc_exit(void)
if (fd != -1) {
dprintf(fd, "******** Start dump %s *******\n", __progname);
dprintf(fd,
- "MT=%d I=%d F=%d U=%d J=%d R=%d X=%d C=%d cache=%u G=%zu\n",
- mopts.malloc_mt, mopts.internal_funcs,
- mopts.malloc_freecheck,
+ "MT=%d M=%u I=%d F=%d U=%d J=%d R=%d X=%d C=%d cache=%u
G=%zu\n",
+ mopts.malloc_mt, mopts.mallloc_mutexes,
+ mopts.internal_funcs, mopts.malloc_freecheck,
mopts.malloc_freeunmap, mopts.malloc_junk,
mopts.malloc_realloc, mopts.malloc_xmalloc,
mopts.chunk_canaries, mopts.malloc_cache,
mopts.malloc_guard);
- for (i = 0; i < _MALLOC_MUTEXES; i++)
+ for (i = 0; i < mopts.malloc_mutexes; i++)
malloc_dump(fd, i, mopts.malloc_pool[i]);
dprintf(fd, "******** End dump %s *******\n", __progname);
close(fd);
Index: thread/rthread_libc.c
===================================================================
RCS file: /cvs/src/lib/libc/thread/rthread_libc.c,v
retrieving revision 1.2
diff -u -p -r1.2 rthread_libc.c
--- thread/rthread_libc.c 5 Sep 2017 02:40:54 -0000 1.2
+++ thread/rthread_libc.c 19 Dec 2018 10:18:38 -0000
@@ -169,14 +169,70 @@ static struct pthread_mutex malloc_lock[
MALLOC_LOCK_INITIALIZER(0),
MALLOC_LOCK_INITIALIZER(1),
MALLOC_LOCK_INITIALIZER(2),
- MALLOC_LOCK_INITIALIZER(3)
+ MALLOC_LOCK_INITIALIZER(3),
+ MALLOC_LOCK_INITIALIZER(4),
+ MALLOC_LOCK_INITIALIZER(5),
+ MALLOC_LOCK_INITIALIZER(6),
+ MALLOC_LOCK_INITIALIZER(7),
+ MALLOC_LOCK_INITIALIZER(8),
+ MALLOC_LOCK_INITIALIZER(9),
+ MALLOC_LOCK_INITIALIZER(10),
+ MALLOC_LOCK_INITIALIZER(11),
+ MALLOC_LOCK_INITIALIZER(12),
+ MALLOC_LOCK_INITIALIZER(13),
+ MALLOC_LOCK_INITIALIZER(14),
+ MALLOC_LOCK_INITIALIZER(15),
+ MALLOC_LOCK_INITIALIZER(16),
+ MALLOC_LOCK_INITIALIZER(17),
+ MALLOC_LOCK_INITIALIZER(18),
+ MALLOC_LOCK_INITIALIZER(19),
+ MALLOC_LOCK_INITIALIZER(20),
+ MALLOC_LOCK_INITIALIZER(21),
+ MALLOC_LOCK_INITIALIZER(22),
+ MALLOC_LOCK_INITIALIZER(23),
+ MALLOC_LOCK_INITIALIZER(24),
+ MALLOC_LOCK_INITIALIZER(25),
+ MALLOC_LOCK_INITIALIZER(26),
+ MALLOC_LOCK_INITIALIZER(27),
+ MALLOC_LOCK_INITIALIZER(28),
+ MALLOC_LOCK_INITIALIZER(29),
+ MALLOC_LOCK_INITIALIZER(30),
+ MALLOC_LOCK_INITIALIZER(31)
};
static pthread_mutex_t malloc_mutex[_MALLOC_MUTEXES] = {
&malloc_lock[0],
&malloc_lock[1],
&malloc_lock[2],
- &malloc_lock[3]
+ &malloc_lock[3],
+ &malloc_lock[4],
+ &malloc_lock[5],
+ &malloc_lock[6],
+ &malloc_lock[7],
+ &malloc_lock[8],
+ &malloc_lock[9],
+ &malloc_lock[10],
+ &malloc_lock[11],
+ &malloc_lock[12],
+ &malloc_lock[13],
+ &malloc_lock[14],
+ &malloc_lock[15],
+ &malloc_lock[16],
+ &malloc_lock[17],
+ &malloc_lock[18],
+ &malloc_lock[19],
+ &malloc_lock[20],
+ &malloc_lock[21],
+ &malloc_lock[22],
+ &malloc_lock[23],
+ &malloc_lock[24],
+ &malloc_lock[25],
+ &malloc_lock[26],
+ &malloc_lock[27],
+ &malloc_lock[28],
+ &malloc_lock[29],
+ &malloc_lock[30],
+ &malloc_lock[31]
};
void
