Author: njn
Date: 2007-10-17 06:10:26 +0100 (Wed, 17 Oct 2007)
New Revision: 7012
Log:
Minimise number of divisions. Shaves a few more seconds off konqueror
startup.
Modified:
branches/MASSIF2/massif/ms_main.c
Modified: branches/MASSIF2/massif/ms_main.c
===================================================================
--- branches/MASSIF2/massif/ms_main.c 2007-10-17 04:36:39 UTC (rev 7011)
+++ branches/MASSIF2/massif/ms_main.c 2007-10-17 05:10:26 UTC (rev 7012)
@@ -87,7 +87,15 @@
// many-xpts 0.09s ma: 2.0s (22.3x, -----)
// konqueror 0:42 real 0:34 user
//
+// Don't do the significance test (which involves a division) for every
+// child, instead compute a threshold (which involves a division) which can
+// be reused for every child of an XPt (r7012):
+// heap 0.60s ma:12.4s (20.6x, -----)
+// tinycc 0.48s ma: 4.8s (10.1x, -----)
+// many-xpts 0.10s ma: 2.2s (22.1x, -----)
+// konqueror 37.7s real 0:29.5s user
//
+//
// Todo:
// - for regtests, need to filter out code addresses in *.post.* files
// - do snapshots on client requests
@@ -632,21 +640,6 @@
: 0);
}
-// Does the xpt account for >= 1% (or so) of total memory used?
-static Bool is_significant_XPt(XPt* xpt, SizeT total_szB)
-{
- // clo_threshold is measured in hundredths of a percent of total size,
- // ie. 10,000ths of total size. So clo_threshold=100 means that the
- // threshold is 1% of total size. If total_szB is zero, we consider
- // every XPt significant. We also always consider the alloc_xpt to be
- // significant.
- tl_assert(xpt->szB <= total_szB);
- return xpt == alloc_xpt || 0 == clo_threshold ||
- (0 != total_szB &&
- // Nb: 10000 is a ULong to avoid possible overflow problems.
- xpt->szB * 10000ULL / total_szB >= clo_threshold);
-}
-
//------------------------------------------------------------//
//--- XTree Operations ---//
//------------------------------------------------------------//
@@ -655,7 +648,7 @@
static SXPt* dup_XTree(XPt* xpt, SizeT total_szB)
{
Int i, n_sig_children, n_insig_children, n_child_sxpts;
- SizeT insig_children_szB;
+ SizeT insig_children_szB, sig_child_threshold_szB;
SXPt* sxpt;
// Number of XPt children Action for SXPT
@@ -665,10 +658,24 @@
// N sig, M insig alloc N+1, dup first N, aggregate remaining M
// 0 sig, M insig alloc 1, aggregate M
+ // Work out how big a child must be to be significant. If the current
+ // total_szB is zero, then we set it to 1, which means everything will be
+ // judged insignificant -- this is sensible, as there's no point showing
+ // any detail for this case. Unless they used --threshold=0, in which
+ // case we show them everything because that's what they asked for.
+ //
+ // Nb: We do this once now, rather than once per child, because if we do
+ // that the cost of all the divisions adds up to something significant.
+ if (total_szB == 0 && clo_threshold != 0) {
+ sig_child_threshold_szB = 1;
+ } else {
+ sig_child_threshold_szB = (((ULong)total_szB) * clo_threshold) /
10000ULL;
+ }
+
// How many children are significant? And do we need an aggregate SXPt?
n_sig_children = 0;
for (i = 0; i < xpt->n_children; i++) {
- if (is_significant_XPt(xpt->children[i], total_szB)) {
+ if (xpt->children[i]->szB >= sig_child_threshold_szB) {
n_sig_children++;
}
}
@@ -692,7 +699,7 @@
// Duplicate the significant children.
j = 0;
for (i = 0; i < xpt->n_children; i++) {
- if (is_significant_XPt(xpt->children[i], total_szB)) {
+ if (xpt->children[i]->szB >= sig_child_threshold_szB) {
sxpt->Sig.children[j++] = dup_XTree(xpt->children[i], total_szB);
sig_children_szB += xpt->children[i]->szB;
}
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