[SCM] Samba Shared Repository - branch master updated
Jeremy Allison
jra at samba.org
Wed Dec 15 01:04:01 UTC 2021
The branch, master has been updated
via 5b526f4533b tdb: Raw performance torture to beat tdb_increment_seqnum
via b9f06ab3472 tdb: Use atomic operations for tdb_[increment|get]_seqnum
via 62dab3921b3 configure: Check for __atomic_add_fetch() and __atomic_load()
from 1dc803048f8 lib/util: Add signal.h include
https://git.samba.org/?p=samba.git;a=shortlog;h=master
- Log -----------------------------------------------------------------
commit 5b526f4533bda42b51326c3b60fd771bc1cd88e7
Author: Volker Lendecke <vl at samba.org>
Date: Mon Dec 13 17:49:51 2021 +0100
tdb: Raw performance torture to beat tdb_increment_seqnum
Running this on sn-devel-184 takes ~14 seconds with the atomic
ops. Without them I did not wait for it to finish. After reducing
NPROCS from 500 to 50 it still ran for more than a minute.
Signed-off-by: Volker Lendecke <vl at samba.org>
Reviewed-by: Jeremy Allison <jra at samba.org>
Autobuild-User(master): Jeremy Allison <jra at samba.org>
Autobuild-Date(master): Wed Dec 15 01:03:56 UTC 2021 on sn-devel-184
commit b9f06ab3472352d064082a44f7d5077c8c13931c
Author: Volker Lendecke <vl at samba.org>
Date: Mon Dec 13 17:42:12 2021 +0100
tdb: Use atomic operations for tdb_[increment|get]_seqnum
With locking.tdb now based on g_lock.c code, we change locking.tdb a
lot more often. I have a customer case where LDX tortures smbd very
hard with 800+ concurrent connections, which now completely falls over
where 4.12 still worked fine. Some debugging showed a thundering herd
on fcntl locking.tdb index 48 (TDB_SEQNUM_OFS). We still use fcntl for
the seqnum, back when we converted the chainlocks to mutexes we did
not consider it to be a problem. Now it is, but all we need to do with
the SEQNUM is to increment it, so an __atomic_add_fetch() of one is
sufficient.
I've taken a look at the C11 standard atomics, but I could not figure
out how to use them properly, to me they seem more general to be
initialized first etc. All we need is a X86 "lock incl 48(%rax)" to be
emitted, and the gcc __atomic_add_fetch seems to do this.
Signed-off-by: Volker Lendecke <vl at samba.org>
Reviewed-by: Jeremy Allison <jra at samba.org>
commit 62dab3921b335d47a0c9c419714d0e2ea2320f74
Author: Volker Lendecke <vl at samba.org>
Date: Mon Dec 13 17:40:52 2021 +0100
configure: Check for __atomic_add_fetch() and __atomic_load()
To be used in the tdb_seqnum code soon
Signed-off-by: Volker Lendecke <vl at samba.org>
Reviewed-by: Jeremy Allison <jra at samba.org>
-----------------------------------------------------------------------
Summary of changes:
lib/replace/wscript | 16 ++++++
lib/tdb/common/tdb.c | 24 +++++++++
lib/tdb/tools/tdbtortseq.c | 123 +++++++++++++++++++++++++++++++++++++++++++++
lib/tdb/wscript | 5 ++
4 files changed, 168 insertions(+)
create mode 100644 lib/tdb/tools/tdbtortseq.c
Changeset truncated at 500 lines:
diff --git a/lib/replace/wscript b/lib/replace/wscript
index a928b80f2f7..e60ff15f903 100644
--- a/lib/replace/wscript
+++ b/lib/replace/wscript
@@ -313,6 +313,22 @@ def configure(conf):
headers='stdint.h sys/atomic.h',
msg='Checking for atomic_add_32 compiler builtin')
+ conf.CHECK_CODE('''
+ uint32_t i,j;
+ j = __atomic_add_fetch(&i,1,__ATOMIC_SEQ_CST)
+ ''',
+ 'HAVE___ATOMIC_ADD_FETCH',
+ headers='stdint.h',
+ msg='Checking for __atomic_add_fetch compiler builtin')
+
+ conf.CHECK_CODE('''
+ uint32_t i,j;
+ __atomic_load(&i,&j,__ATOMIC_SEQ_CST)
+ ''',
+ 'HAVE___ATOMIC_ADD_LOAD',
+ headers='stdint.h',
+ msg='Checking for __atomic_load compiler builtin')
+
# Check for thread fence. */
tf = conf.CHECK_CODE('atomic_thread_fence(memory_order_seq_cst);',
'HAVE_ATOMIC_THREAD_FENCE',
diff --git a/lib/tdb/common/tdb.c b/lib/tdb/common/tdb.c
index c56b37be5ca..de829bb48c4 100644
--- a/lib/tdb/common/tdb.c
+++ b/lib/tdb/common/tdb.c
@@ -64,6 +64,15 @@ static void tdb_increment_seqnum(struct tdb_context *tdb)
return;
}
+#if defined(HAVE___ATOMIC_ADD_FETCH) && defined(HAVE___ATOMIC_ADD_LOAD)
+ if (tdb->map_ptr != NULL) {
+ uint32_t *pseqnum = (uint32_t *)(
+ TDB_SEQNUM_OFS + (char *)tdb->map_ptr);
+ __atomic_add_fetch(pseqnum, 1, __ATOMIC_SEQ_CST);
+ return;
+ }
+#endif
+
if (tdb_nest_lock(tdb, TDB_SEQNUM_OFS, F_WRLCK,
TDB_LOCK_WAIT|TDB_LOCK_PROBE) != 0) {
return;
@@ -838,6 +847,21 @@ _PUBLIC_ int tdb_get_seqnum(struct tdb_context *tdb)
{
tdb_off_t seqnum=0;
+ if (tdb->transaction != NULL) {
+ tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &seqnum);
+ return seqnum;
+ }
+
+#if defined(HAVE___ATOMIC_ADD_FETCH) && defined(HAVE___ATOMIC_ADD_LOAD)
+ if (tdb->map_ptr != NULL) {
+ uint32_t *pseqnum = (uint32_t *)(
+ TDB_SEQNUM_OFS + (char *)tdb->map_ptr);
+ uint32_t ret;
+ __atomic_load(pseqnum, &ret,__ATOMIC_SEQ_CST);
+ return ret;
+ }
+#endif
+
tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &seqnum);
return seqnum;
}
diff --git a/lib/tdb/tools/tdbtortseq.c b/lib/tdb/tools/tdbtortseq.c
new file mode 100644
index 00000000000..9423b46d996
--- /dev/null
+++ b/lib/tdb/tools/tdbtortseq.c
@@ -0,0 +1,123 @@
+/*
+ * Unix SMB/CIFS implementation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "replace.h"
+#include "system/filesys.h"
+#include <tdb.h>
+#include <stdio.h>
+#include <errno.h>
+#include "system/wait.h"
+
+#define NPROCS 500
+#define NUMOPS 1000000
+
+int main(void)
+{
+ pid_t pids[NPROCS];
+ struct tdb_context *tdb = NULL;
+ int i;
+ uint32_t seqnum_before, seqnum_after;
+
+ tdb = tdb_open("seqnum_test.tdb",
+ 10000,
+ TDB_CLEAR_IF_FIRST|
+ TDB_SEQNUM|
+ TDB_INCOMPATIBLE_HASH|
+ TDB_MUTEX_LOCKING,
+ O_CREAT|O_RDWR,
+ 0644);
+ if (tdb == NULL) {
+ perror("tdb_open failed");
+ return 1;
+ }
+ seqnum_before = tdb_get_seqnum(tdb);
+
+ for (i=0; i<NPROCS; i++) {
+ pids[i] = fork();
+ if (pids[i] == -1) {
+ perror("fork failed");
+ return 1;
+ }
+ if (pids[i] == 0) {
+ pid_t mypid = getpid();
+ int ret;
+ int j;
+
+ ret = tdb_reopen(tdb);
+ if (ret != 0) {
+ perror("tdb_reopen failed");
+ return 1;
+ }
+
+ for (j=0; j<NUMOPS; j++) {
+ TDB_DATA key = {
+ .dptr = (uint8_t *)&mypid,
+ .dsize = sizeof(mypid),
+ };
+ TDB_DATA value = {
+ .dptr = (uint8_t *)&j,
+ .dsize = sizeof(j),
+ };
+ ret = tdb_store(tdb, key, value, 0);
+ if (ret == -1) {
+ perror("tdb_store failed");
+ return 1;
+ }
+ }
+
+ return 0;
+ }
+ }
+
+ for (i=0; i<NPROCS; i++) {
+ int wstatus;
+ pid_t ret = waitpid(pids[i], &wstatus, 0);
+
+ if (ret == -1) {
+ perror("waitpid failed");
+ return 1;
+ }
+
+ if (!WIFEXITED(wstatus)) {
+ fprintf(stderr,
+ "pid %d did not exit properly\n",
+ (int)pids[i]);
+ return 1;
+ }
+
+ if (WEXITSTATUS(wstatus) != 0) {
+ fprintf(stderr,
+ "pid %d returned %d\n",
+ (int)pids[i],
+ WEXITSTATUS(wstatus));
+ return 1;
+ }
+ }
+
+ seqnum_after = tdb_get_seqnum(tdb);
+
+ printf("seqnum_before=%"PRIu32", seqnum_after=%"PRIu32"\n",
+ seqnum_before,
+ seqnum_after);
+
+ if ((seqnum_after - seqnum_before) != (NPROCS*NUMOPS)) {
+ perror("incrementing seqnum failed");
+ return 1;
+ }
+
+ return 0;
+}
diff --git a/lib/tdb/wscript b/lib/tdb/wscript
index 19b256f037c..81132dc3276 100644
--- a/lib/tdb/wscript
+++ b/lib/tdb/wscript
@@ -145,6 +145,11 @@ def build(bld):
'tdb',
install=False)
+ bld.SAMBA_BINARY('tdbtortseq',
+ 'tools/tdbtortseq.c',
+ 'tdb',
+ install=False)
+
bld.SAMBA_BINARY('tdbrestore',
'tools/tdbrestore.c',
'tdb', manpages='man/tdbrestore.8')
--
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