From: Julian Seward <jseward@acm.org>
Date: Sat, 12 Mar 2005 15:16:31 +0000 (+0000)
Subject: Fix yielding properly.
X-Git-Tag: svn/VALGRIND_3_0_0~1017
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f03dd1e3856f99a9ffeb2f3da290c7fba1589496;p=thirdparty%2Fvalgrind.git

Fix yielding properly.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@3301
---

diff --git a/coregrind/vg_scheduler.c b/coregrind/vg_scheduler.c
index 4d5a71bf10..debf2cd2dc 100644
--- a/coregrind/vg_scheduler.c
+++ b/coregrind/vg_scheduler.c
@@ -780,8 +780,14 @@ VgSchedReturnCode VG_(scheduler) ( ThreadId tid )
 
       case VEX_TRC_JMP_YIELD:
 	 /* Explicit yield, because this thread is in a spin-lock
-	    or something.  Let another thread run ASAP. */
-	 VG_(dispatch_ctr) = 1;
+	    or something.  Only let the thread run for a short while
+            longer.  Because swapping to another thread is expensive,
+            we're prepared to let this thread eat a little more CPU
+            before swapping to another.  That means that short term
+            spins waiting for hardware to poke memory won't cause a
+            thread swap. */
+	 if (VG_(dispatch_ctr) > 100) 
+            VG_(dispatch_ctr) = 100;
 	 break;
 
       case VG_TRC_INNER_COUNTERZERO: