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Added more control over write barrier. in particular separated scans after a hit.

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Copied from Perforce
 Change: 186988
 ServerID: perforce.ravenbrook.com
This commit is contained in:
David Lovemore 2014-08-27 11:21:18 +01:00
parent 46d723c9dc
commit b4460043e6
4 changed files with 21 additions and 13 deletions
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16
mps/code/trace.c
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@ -1105,7 +1105,6 @@ static Res traceScanSegRes(TraceSet ts, Rank rank, Arena arena, Seg seg)
} else { /* scan it */
ScanStateStruct ssStruct;
ScanState ss = &ssStruct;
Bool considerBarrier = FALSE;
ScanStateInit(ss, ts, arena, rank, white);
/* Expose the segment to make sure we can scan it. */
@ -1138,16 +1137,14 @@ static Res traceScanSegRes(TraceSet ts, Rank rank, Arena arena, Seg seg)
AVER(RefSetSub(ScanStateUnfixedSummary(ss), SegSummary(seg)));
if (ZoneSetInter(ScanStateUnfixedSummary(ss), white) == ZoneSetEMPTY) {
/* a scan was not necessary */
if (((GCSeg)seg)->unnecessaryScans < TRACE_SCAN_BARRIER_THRESHOLD) {
((GCSeg)seg)->unnecessaryScans++;
} else {
considerBarrier = TRUE;
}
if (seg->scans > 0)
seg->scans--;
} else {
((GCSeg)seg)->unnecessaryScans = 0;
if (seg->scans < SEG_SCANS_AFTER_NEEDED_SCAN)
seg->scans = SEG_SCANS_AFTER_NEEDED_SCAN;
}
if (considerBarrier) {
if (seg->scans == 0) {
if(res != ResOK || !wasTotal) {
/* scan was partial, so... */
/* scanned summary should be ORed into segment summary. */
@ -1217,6 +1214,9 @@ void TraceSegAccess(Arena arena, Seg seg, AccessSet mode)
EVENT3(TraceAccess, arena, seg, mode);
if ((mode & SegSM(seg) & AccessWRITE) != 0) /* write barrier? */
seg->scans = SEG_SCANS_AFTER_HIT;
if((mode & SegSM(seg) & AccessREAD) != 0) { /* read barrier? */
Trace trace;
TraceId ti;