X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=rts%2FCapability.h;h=d2fcc5ed7bfdb90449773560938618a59cc18a72;hb=de75026f5a48d3d052135a973ab4dff76c5b20f5;hp=478b0f1312e8a9e4aca1bdf6cf9b06041d8c1b8f;hpb=3ebcd3deb769a03f4ded0fca2cf38201048c0214;p=ghc-hetmet.git

diff --git a/rts/Capability.h b/rts/Capability.h
index 478b0f1..d2fcc5e 100644
--- a/rts/Capability.h
+++ b/rts/Capability.h
@@ -32,11 +32,7 @@ struct Capability_ {
     // code.  During STG execution, the BaseReg register always points
     // to the StgRegTable of the current Capability (&cap->r).
     StgFunTable f;
-    StgRegTable r GNU_ATTRIBUTE(packed);
-       // packed eliminates any padding between f and r.  Not strictly
-       // necessary, but it means the negative offsets for accessing
-       // the fields of f when we are in STG code are as small as
-       // possible.
+    StgRegTable r;
 
     nat no;  // capability number.
 
@@ -69,10 +65,12 @@ struct Capability_ {
     Task *suspended_ccalling_tasks;
 
     // One mutable list per generation, so we don't need to take any
-    // locks when updating an old-generation thunk.  These
-    // mini-mut-lists are moved onto the respective gen->mut_list at
-    // each GC.
+    // locks when updating an old-generation thunk.  This also lets us
+    // keep track of which closures this CPU has been mutating, so we
+    // can traverse them using the right thread during GC and avoid
+    // unnecessarily moving the data from one cache to another.
     bdescr **mut_lists;
+    bdescr **saved_mut_lists; // tmp use during GC
 
     // Context switch flag. We used to have one global flag, now one 
     // per capability. Locks required  : none (conflicts are harmless)
@@ -147,12 +145,10 @@ struct Capability_ {
 
 // Converts a *StgRegTable into a *Capability.
 //
-#define OFFSET(s_type, field) ((size_t)&(((s_type*)0)->field))
-
 INLINE_HEADER Capability *
 regTableToCapability (StgRegTable *reg)
 {
-    return (Capability *)((void *)((unsigned char*)reg - OFFSET(Capability,r)));
+    return (Capability *)((void *)((unsigned char*)reg - STG_FIELD_OFFSET(Capability,r)));
 }
 
 // Initialise the available capabilities.
@@ -280,6 +276,7 @@ extern void grabCapability (Capability **pCap);
 
 // cause all capabilities to context switch as soon as possible.
 void setContextSwitches(void);
+INLINE_HEADER void contextSwitchCapability(Capability *cap);
 
 // Free all capabilities
 void freeCapabilities (void);
@@ -326,4 +323,16 @@ discardSparksCap (Capability *cap)
 { return discardSparks(cap->sparks); }
 #endif
 
+INLINE_HEADER void
+contextSwitchCapability (Capability *cap)
+{
+    // setting HpLim to NULL ensures that the next heap check will
+    // fail, and the thread will return to the scheduler.
+    cap->r.rHpLim = NULL;
+    // But just in case it didn't work (the target thread might be
+    // modifying HpLim at the same time), we set the end-of-block
+    // context-switch flag too:
+    cap->context_switch = 1;
+}
+
 #endif /* CAPABILITY_H */