Josh Berkus wrote:
> On 12/6/10 6:10 PM, Tom Lane wrote:
> > Robert Haas <[email protected]> writes:
> >> On Mon, Dec 6, 2010 at 9:04 PM, Josh Berkus <[email protected]> wrote:
> >>> Actually, on OSX 10.5.8, o_dsync and fdatasync aren't even available.
> >>> From my run, it looks like even so regular fsync might be better than
> >>> open_sync.
> >
> >> But I think you need to use fsync_writethrough if you actually want
> >> durability.
> >
> > Yeah. Unless your laptop contains an SSD, those numbers are garbage on
> > their face. So that's another problem with test_fsync: it omits
> > fsync_writethrough.
>
> Yeah, the issue with test_fsync appears to be that it's designed to work
> without os-specific switches no matter what, not to accurately reflect
> how we access wal.
I have now modified pg_test_fsync to use O_DIRECT for O_SYNC/O_FSYNC,
and O_DSYNC, if supported, so it now matches how we use WAL (except we
don't use O_DIRECT when in 'archive' and 'hot standby' mode). Applied
patch attached.
--
Bruce Momjian <[email protected]> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ It's impossible for everything to be true. +
diff --git a/contrib/pg_test_fsync/pg_test_fsync.c b/contrib/pg_test_fsync/pg_test_fsync.c
new file mode 100644
index d075483..49a7b3c
*** a/contrib/pg_test_fsync/pg_test_fsync.c
--- b/contrib/pg_test_fsync/pg_test_fsync.c
***************
*** 23,29 ****
#define XLOG_BLCKSZ_K (XLOG_BLCKSZ / 1024)
#define LABEL_FORMAT " %-32s"
! #define NA_FORMAT LABEL_FORMAT "%18s"
#define OPS_FORMAT "%9.3f ops/sec"
static const char *progname;
--- 23,29 ----
#define XLOG_BLCKSZ_K (XLOG_BLCKSZ / 1024)
#define LABEL_FORMAT " %-32s"
! #define NA_FORMAT "%18s"
#define OPS_FORMAT "%9.3f ops/sec"
static const char *progname;
*************** handle_args(int argc, char *argv[])
*** 134,139 ****
--- 134,144 ----
}
printf("%d operations per test\n", ops_per_test);
+ #if PG_O_DIRECT != 0
+ printf("O_DIRECT supported on this platform for open_datasync and open_sync.\n");
+ #else
+ printf("Direct I/O is not supported on this platform.\n");
+ #endif
}
static void
*************** test_sync(int writes_per_op)
*** 184,226 ****
/*
* Test open_datasync if available
*/
! #ifdef OPEN_DATASYNC_FLAG
! printf(LABEL_FORMAT, "open_datasync"
! #if PG_O_DIRECT != 0
! " (non-direct I/O)*"
! #endif
! );
fflush(stdout);
! if ((tmpfile = open(filename, O_RDWR | O_DSYNC, 0)) == -1)
! die("could not open output file");
! gettimeofday(&start_t, NULL);
! for (ops = 0; ops < ops_per_test; ops++)
! {
! for (writes = 0; writes < writes_per_op; writes++)
! if (write(tmpfile, buf, XLOG_BLCKSZ) != XLOG_BLCKSZ)
! die("write failed");
! if (lseek(tmpfile, 0, SEEK_SET) == -1)
! die("seek failed");
! }
! gettimeofday(&stop_t, NULL);
! close(tmpfile);
! print_elapse(start_t, stop_t);
!
! /*
! * If O_DIRECT is enabled, test that with open_datasync
! */
! #if PG_O_DIRECT != 0
if ((tmpfile = open(filename, O_RDWR | O_DSYNC | PG_O_DIRECT, 0)) == -1)
{
! printf(NA_FORMAT, "o_direct", "n/a**\n");
fs_warning = true;
}
else
{
! printf(LABEL_FORMAT, "open_datasync (direct I/O)");
! fflush(stdout);
!
gettimeofday(&start_t, NULL);
for (ops = 0; ops < ops_per_test; ops++)
{
--- 189,207 ----
/*
* Test open_datasync if available
*/
! printf(LABEL_FORMAT, "open_datasync");
fflush(stdout);
! #ifdef OPEN_DATASYNC_FLAG
if ((tmpfile = open(filename, O_RDWR | O_DSYNC | PG_O_DIRECT, 0)) == -1)
{
! printf(NA_FORMAT, "n/a*\n");
fs_warning = true;
}
else
{
! if ((tmpfile = open(filename, O_RDWR | O_DSYNC | PG_O_DIRECT, 0)) == -1)
! die("could not open output file");
gettimeofday(&start_t, NULL);
for (ops = 0; ops < ops_per_test; ops++)
{
*************** test_sync(int writes_per_op)
*** 234,252 ****
close(tmpfile);
print_elapse(start_t, stop_t);
}
- #endif
-
#else
! printf(NA_FORMAT, "open_datasync", "n/a\n");
#endif
/*
* Test fdatasync if available
*/
- #ifdef HAVE_FDATASYNC
printf(LABEL_FORMAT, "fdatasync");
fflush(stdout);
if ((tmpfile = open(filename, O_RDWR, 0)) == -1)
die("could not open output file");
gettimeofday(&start_t, NULL);
--- 215,231 ----
close(tmpfile);
print_elapse(start_t, stop_t);
}
#else
! printf(NA_FORMAT, "n/a\n");
#endif
/*
* Test fdatasync if available
*/
printf(LABEL_FORMAT, "fdatasync");
fflush(stdout);
+ #ifdef HAVE_FDATASYNC
if ((tmpfile = open(filename, O_RDWR, 0)) == -1)
die("could not open output file");
gettimeofday(&start_t, NULL);
*************** test_sync(int writes_per_op)
*** 263,269 ****
close(tmpfile);
print_elapse(start_t, stop_t);
#else
! printf(NA_FORMAT, "fdatasync", "n/a\n");
#endif
/*
--- 242,248 ----
close(tmpfile);
print_elapse(start_t, stop_t);
#else
! printf(NA_FORMAT, "n/a\n");
#endif
/*
*************** test_sync(int writes_per_op)
*** 292,301 ****
/*
* If fsync_writethrough is available, test as well
*/
- #ifdef HAVE_FSYNC_WRITETHROUGH
printf(LABEL_FORMAT, "fsync_writethrough");
fflush(stdout);
if ((tmpfile = open(filename, O_RDWR, 0)) == -1)
die("could not open output file");
gettimeofday(&start_t, NULL);
--- 271,280 ----
/*
* If fsync_writethrough is available, test as well
*/
printf(LABEL_FORMAT, "fsync_writethrough");
fflush(stdout);
+ #ifdef HAVE_FSYNC_WRITETHROUGH
if ((tmpfile = open(filename, O_RDWR, 0)) == -1)
die("could not open output file");
gettimeofday(&start_t, NULL);
*************** test_sync(int writes_per_op)
*** 313,361 ****
close(tmpfile);
print_elapse(start_t, stop_t);
#else
! printf(NA_FORMAT, "fsync_writethrough", "n/a\n");
#endif
/*
* Test open_sync if available
*/
! #ifdef OPEN_SYNC_FLAG
! printf(LABEL_FORMAT, "open_sync"
! #if PG_O_DIRECT != 0
! " (non-direct I/O)*"
! #endif
! );
fflush(stdout);
! if ((tmpfile = open(filename, O_RDWR | OPEN_SYNC_FLAG, 0)) == -1)
! die("could not open output file");
! gettimeofday(&start_t, NULL);
! for (ops = 0; ops < ops_per_test; ops++)
! {
! for (writes = 0; writes < writes_per_op; writes++)
! if (write(tmpfile, buf, XLOG_BLCKSZ) != XLOG_BLCKSZ)
! die("write failed");
! if (lseek(tmpfile, 0, SEEK_SET) == -1)
! die("seek failed");
! }
! gettimeofday(&stop_t, NULL);
! close(tmpfile);
! print_elapse(start_t, stop_t);
!
! /*
! * If O_DIRECT is enabled, test that with open_sync
! */
! #if PG_O_DIRECT != 0
if ((tmpfile = open(filename, O_RDWR | OPEN_SYNC_FLAG | PG_O_DIRECT, 0)) == -1)
{
! printf(NA_FORMAT, "o_direct", "n/a**\n");
fs_warning = true;
}
else
{
- printf(LABEL_FORMAT, "open_sync (direct I/O)");
- fflush(stdout);
-
gettimeofday(&start_t, NULL);
for (ops = 0; ops < ops_per_test; ops++)
{
--- 292,314 ----
close(tmpfile);
print_elapse(start_t, stop_t);
#else
! printf(NA_FORMAT, "n/a\n");
#endif
/*
* Test open_sync if available
*/
! printf(LABEL_FORMAT, "open_sync");
fflush(stdout);
! #ifdef OPEN_SYNC_FLAG
if ((tmpfile = open(filename, O_RDWR | OPEN_SYNC_FLAG | PG_O_DIRECT, 0)) == -1)
{
! printf(NA_FORMAT, "n/a*\n");
fs_warning = true;
}
else
{
gettimeofday(&start_t, NULL);
for (ops = 0; ops < ops_per_test; ops++)
{
*************** test_sync(int writes_per_op)
*** 369,388 ****
close(tmpfile);
print_elapse(start_t, stop_t);
}
- #endif
-
#else
! printf(NA_FORMAT, "open_sync", "n/a\n");
! #endif
!
! #if defined(OPEN_DATASYNC_FLAG) || defined(OPEN_SYNC_FLAG)
! if (PG_O_DIRECT != 0)
! printf("* This non-direct I/O mode is not used by Postgres.\n");
#endif
if (fs_warning)
{
! printf("** This file system and its mount options do not support direct\n");
printf("I/O, e.g. ext4 in journaled mode.\n");
}
}
--- 322,334 ----
close(tmpfile);
print_elapse(start_t, stop_t);
}
#else
! printf(NA_FORMAT, "n/a\n");
#endif
if (fs_warning)
{
! printf("* This file system and its mount options do not support direct\n");
printf("I/O, e.g. ext4 in journaled mode.\n");
}
}
*************** test_open_syncs(void)
*** 407,422 ****
static void
test_open_sync(const char *msg, int writes_size)
{
- #ifdef OPEN_SYNC_FLAG
int tmpfile, ops, writes;
if ((tmpfile = open(filename, O_RDWR | OPEN_SYNC_FLAG | PG_O_DIRECT, 0)) == -1)
! printf(NA_FORMAT, "o_direct", "n/a**\n");
else
{
- printf(LABEL_FORMAT, msg);
- fflush(stdout);
-
gettimeofday(&start_t, NULL);
for (ops = 0; ops < ops_per_test; ops++)
{
--- 353,368 ----
static void
test_open_sync(const char *msg, int writes_size)
{
int tmpfile, ops, writes;
+ printf(LABEL_FORMAT, msg);
+ fflush(stdout);
+
+ #ifdef OPEN_SYNC_FLAG
if ((tmpfile = open(filename, O_RDWR | OPEN_SYNC_FLAG | PG_O_DIRECT, 0)) == -1)
! printf(NA_FORMAT, "n/a*\n");
else
{
gettimeofday(&start_t, NULL);
for (ops = 0; ops < ops_per_test; ops++)
{
*************** test_open_sync(const char *msg, int writ
*** 433,439 ****
}
#else
! printf(NA_FORMAT, "open_sync", "n/a\n");
#endif
}
--- 379,385 ----
}
#else
! printf(NA_FORMAT, "n/a\n");
#endif
}
--
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