Changeset: e79b2edeba71 for MonetDB
URL: http://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=e79b2edeba71
Modified Files:
monetdb5/mal/mal.c
monetdb5/mal/mal.h
monetdb5/mal/mal_interpreter.c
Branch: Feb2013
Log Message:
Limit the number of concurrent queries
The total throughput for small (and large) queries is
improved if we limit the number of concurrent queries
being executed. This patch is geared at SQL, wrapping
callMAL with a semaphore to limit the level of parallelism
to number of physical cores.
diffs (59 lines):
diff --git a/monetdb5/mal/mal.c b/monetdb5/mal/mal.c
--- a/monetdb5/mal/mal.c
+++ b/monetdb5/mal/mal.c
@@ -195,6 +195,7 @@ MT_Lock mal_remoteLock;
MT_Lock mal_profileLock ;
MT_Lock mal_copyLock;
MT_Lock mal_delayLock;
+MT_Sema mal_parallelism;
/*
* Initialization of the MAL context
* The compiler directive STRUCT_ALIGNED tells that the
@@ -233,6 +234,7 @@ int mal_init(void){
MT_lock_init( &mal_profileLock, "mal_profileLock");
MT_lock_init( &mal_copyLock, "mal_copyLock");
MT_lock_init( &mal_delayLock, "mal_delayLock");
+ MT_sema_init( &mal_parallelism, (GDKnr_threads ? GDKnr_threads/2: 4),
"mal_parallelism");
tstAligned();
MCinit();
diff --git a/monetdb5/mal/mal.h b/monetdb5/mal/mal.h
--- a/monetdb5/mal/mal.h
+++ b/monetdb5/mal/mal.h
@@ -118,6 +118,7 @@ mal_export MT_Lock mal_remoteLock;
mal_export MT_Lock mal_profileLock ;
mal_export MT_Lock mal_copyLock ;
mal_export MT_Lock mal_delayLock ;
+mal_export MT_Sema mal_parallelism;
mal_export int mal_init(void);
diff --git a/monetdb5/mal/mal_interpreter.c b/monetdb5/mal/mal_interpreter.c
--- a/monetdb5/mal/mal_interpreter.c
+++ b/monetdb5/mal/mal_interpreter.c
@@ -479,7 +479,13 @@ callMAL(Client cntxt, MalBlkPtr mb, MalS
ValPtr lhs;
InstrPtr pci = getInstrPtr(mb, 0);
RuntimeProfileRecord runtimeProfile;
-
+
+/*
+ * Control the level of parallelism. The maximum number of concurrent MAL plans
+ * is determined by an environment variable. It is initially set equal to the
+ * number of cores, which may be too coarse.
+ */
+ MT_sema_down(&mal_parallelism,"mal_parallelism");
runtimeProfileInit(mb, &runtimeProfile, cntxt->flags & memoryFlag);
#ifdef DEBUG_CALLMAL
mnstr_printf(cntxt->fdout, "callMAL\n");
@@ -518,8 +524,10 @@ callMAL(Client cntxt, MalBlkPtr mb, MalS
case PATcall:
case CMDcall:
default:
+ MT_sema_up(&mal_parallelism,"mal_parallelism");
throw(MAL, "mal.interpreter", RUNTIME_UNKNOWN_INSTRUCTION);
}
+ MT_sema_up(&mal_parallelism,"mal_parallelism");
if (cntxt->qtimeout && time(NULL) - stk->clock.tv_usec >
cntxt->qtimeout)
throw(MAL, "mal.interpreter", RUNTIME_QRY_TIMEOUT);
return ret;
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