Changeset 211111 in webkit

Timestamp:

Jan 24, 2017, 2:07:34 PM (10 years ago)

Author:

fpizlo@apple.com

Message:

Enable the stochastic space-time scheduler on the larger multicores
​https://bugs.webkit.org/show_bug.cgi?id=167382
<rdar://problem/30173375>

Rubber stamped by Saam Barati

This looks like a 1.3% JetStream speed-up thanks to a 28% splay-latency improvement. This new
scheduler seems to prevent all of the same pathologies as the old one prevented. But instead of
periodically suspending the mutator, this new one will only suspend after an iteration of the
constraint fixpoint. The length of that suspension length is random with the distribution being
governed by mutatorUtilization. Once resumed, the mutator gets to run unimpeded until draining
stalls.

I'm enabling it on platforms as I benchmark those platforms. It's possible that we will want to
use a different scheduler on different platforms.

• runtime/Options.cpp:

(JSC::overrideDefaults):

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• runtime/Options.cpp (modified) (1 diff)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2017-01-24  Filip Pizlo  <fpizlo@apple.com>
+
+        Enable the stochastic space-time scheduler on the larger multicores
+        https://bugs.webkit.org/show_bug.cgi?id=167382
+        <rdar://problem/30173375>
+
+        Rubber stamped by Saam Barati
+        
+        This looks like a 1.3% JetStream speed-up thanks to a 28% splay-latency improvement. This new
+        scheduler seems to prevent all of the same pathologies as the old one prevented. But instead of
+        periodically suspending the mutator, this new one will only suspend after an iteration of the
+        constraint fixpoint. The length of that suspension length is random with the distribution being
+        governed by mutatorUtilization. Once resumed, the mutator gets to run unimpeded until draining
+        stalls.
+        
+        I'm enabling it on platforms as I benchmark those platforms. It's possible that we will want to
+        use a different scheduler on different platforms.
+
+        * runtime/Options.cpp:
+        (JSC::overrideDefaults):
+
 2017-01-24  Michael Saboff  <msaboff@apple.com>
 

trunk/Source/JavaScriptCore/runtime/Options.cpp

@@ -313 +313 @@
         Options::concurrentGCMaxHeadroom() = 1.4;
         Options::concurrentGCPeriodMS() = 10;
-    }
+    } else
+        Options::useStochasticMutatorScheduler() = true;
 }