On 03/16/09 13:39, Simon Riggs wrote:
On Wed, 2009-03-11 at 22:20 -0400, Jignesh K. Shah wrote:
A tunable does not impact existing behavior
Why not put the tunable parameter into the patch and then show the test
results with it in? If there is no overhead, we should then be able to
see that.
I did a patch where I define lock_wakeup_algorithm with default value of
0, and range is 0 to 32
It basically handles three types of algorithms and 32 different
permutations, such that:
When lock_wakeup_algorithm is set to
0 => default logic of wakeup (only 1 exclusive or all
sequential shared)
1 => wake up all sequential exclusives or all sequential
shared
32>= n >=2 => wake up first n waiters irrespective of exclusive or
sequential
I did a quick test with patch. Unfortunately it improves my number even
with default setting 0 (not sure whether I should be pleased or sad -
Definitely no overhead infact seems to help performance a bit. NOTE:
Logic is same, implementation is slightly different for default set)
my Prepatch numbers typically peaked around 136,000 tpm
With the patch and settings:
lock_wakeup_algorithm=0
PEAK: 962: 512: Medium Throughput: 161121.000 Avg Medium Resp: 0.051
When lock_wakeup_algorithm=1
Then my PEAK increases to
PEAK 1560: 832: Medium Throughput: 176577.000 Avg Medium Resp: 0.086
(Couldn't recreate the 184K+ result.. need to check that)
I still havent tested for the rest 2-32 values but you get the point,
the patch is quite flexible with various types of permutations and no
overhead.
Do give it a try on your own setup and play with values and compare it
with your original builds.
Regards,
Jignesh
*** lwlock.c Tue Mar 17 12:27:49 2009
--- lwlock.c.orig Wed Mar 11 12:48:27 2009
***************
*** 87,93 ****
static int lock_addin_request = 0;
static bool lock_addin_request_allowed = true;
- int LWLockWakeupAlgorithm;
#ifdef LWLOCK_STATS
static int counts_for_pid = 0;
--- 87,92 ----
***************
*** 564,570 ****
PGPROC *head;
PGPROC *proc;
int i;
- int runq;
PRINT_LWDEBUG("LWLockRelease", lockid, lock);
--- 563,568 ----
***************
*** 612,631 ****
* as many waiters as want shared access.
*/
proc = head;
! if (LWLockWakeupAlgorithm || !proc->lwExclusive)
! {
! if (LWLockWakeupAlgorithm <= 1)
! {
while (proc->lwWaitLink != NULL &&
! (proc->lwExclusive ==
proc->lwWaitLink->lwExclusive))
proc = proc->lwWaitLink;
- }
- else
- {
- runq= LWLockWakeupAlgorithm;
- while (proc->lwWaitLink != NULL && --runq)
- proc = proc->lwWaitLink;
- }
}
/* proc is now the last PGPROC to be released */
lock->head = proc->lwWaitLink;
--- 610,620 ----
* as many waiters as want shared access.
*/
proc = head;
! if (!proc->lwExclusive)
! {
while (proc->lwWaitLink != NULL &&
! !proc->lwWaitLink->lwExclusive)
proc = proc->lwWaitLink;
}
/* proc is now the last PGPROC to be released */
lock->head = proc->lwWaitLink;
*** lwlock.h.orig Tue Mar 17 14:27:10 2009
--- lwlock.h Tue Mar 17 08:24:40 2009
***************
*** 103,106 ****
--- 103,107 ----
extern void RequestAddinLWLocks(int n);
+ extern int LWLockWakeupAlgorithm;
#endif /* LWLOCK_H */
*** guc.c.orig Tue Mar 17 07:30:26 2009
--- guc.c Tue Mar 17 07:47:10 2009
***************
*** 57,62 ****
--- 57,63 ----
#include "postmaster/walwriter.h"
#include "regex/regex.h"
#include "storage/bufmgr.h"
+ #include "storage/lwlock.h"
#include "storage/fd.h"
#include "tcop/tcopprot.h"
#include "tsearch/ts_cache.h"
***************
*** 167,172 ****
--- 168,174 ----
static bool assign_maxconnections(int newval, bool doit, GucSource source);
static bool assign_autovacuum_max_workers(int newval, bool doit, GucSource
source);
static bool assign_effective_io_concurrency(int newval, bool doit, GucSource
source);
+ static bool assign_lock_wakeup_algorithm(int newval, bool doit, GucSource
source);
static const char *assign_pgstat_temp_directory(const char *newval, bool
doit, GucSource source);
static char *config_enum_get_options(struct config_enum *record,
***************
*** 416,421 ****
--- 418,424 ----
static int wal_segment_size;
static bool integer_datetimes;
static int effective_io_concurrency;
+ static int lock_wakeup_algorithm;
/* should be static, but commands/variable.c needs to get at these */
char *role_string;
***************
*** 1727,1732 ****
--- 1730,1745 ----
},
{
+ {"lock_wakeup_algorithm", PGC_USERSET, RESOURCES,
+ gettext_noop("Select algorithm for lock waiters wakeup.
0 is default"),
+ gettext_noop("Select 1 for SMP systems, and higher for
manual conrol of number of waiters to wake up.")
+ },
+ &lock_wakeup_algorithm,
+ 0, 0, 32,
+ assign_lock_wakeup_algorithm, NULL
+ },
+
+ {
{"log_rotation_age", PGC_SIGHUP, LOGGING_WHERE,
gettext_noop("Automatic log file rotation will occur
after N minutes."),
NULL,
***************
*** 7668,7673 ****
--- 7681,7698 ----
#endif /* USE_PREFETCH */
}
+ static bool
+ assign_lock_wakeup_algorithm(int newval, bool doit, GucSource source)
+ {
+ if ( newval < 0 && newval > 32)
+ return false;
+
+ if (doit)
+ LWLockWakeupAlgorithm= newval ;
+
+ return true;
+ }
+
static const char *
assign_pgstat_temp_directory(const char *newval, bool doit, GucSource source)
{
--
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