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Bug 820401 - Default DMD to sample-below=4093. r=njn

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Also print out the sample size, since it's no longer explicit in the $DMD envvar.
This commit is contained in:
Justin Lebar 2012-12-11 18:26:43 -05:00
parent 51d407db90
commit 954ddb8201
2 changed files with 29 additions and 4 deletions
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29
memory/replace/dmd/DMD.cpp
View File

@ -1311,6 +1311,22 @@ OptionLong(const char* aArg, const char* aOptionName, long aMin, long aMax,
static const size_t gMaxSampleBelowSize = 100 * 1000 * 1000; // bytes
// Default to sampling with a sample-below size that's a prime number close to
// 4096.
//
// Using a sample-below size ~= 4096 is much faster than using a sample-below
// size of 1, and it's not much less accurate in practice, so it's a reasonable
// default.
//
// Using a prime sample-below size makes our sampling more random. If we used
// instead a sample-below size of 4096, for example, then if all our allocation
// sizes were even (which they likely are, due to how jemalloc rounds up), our
// alloc counter would take on only even values.
//
// In contrast, using a prime sample-below size lets us explore all possible
// values of the alloc counter.
static const size_t gDefaultSampleBelowSize = 4093;
static void
BadArg(const char* aArg)
{
@ -1324,8 +1340,9 @@ BadArg(const char* aArg)
StatusMsg(" enables it with non-default options.\n");
StatusMsg("\n");
StatusMsg("The following options are allowed; defaults are shown in [].\n");
StatusMsg(" --sample-below=<1..%d> Sample blocks smaller than this [1]\n",
int(gMaxSampleBelowSize));
StatusMsg(" --sample-below=<1..%d> Sample blocks smaller than this [%d]\n"
" (prime numbers recommended).\n",
int(gMaxSampleBelowSize), int(gDefaultSampleBelowSize));
StatusMsg(" --mode=<normal|test|stress> Which mode to run in? [normal]\n");
StatusMsg("\n");
exit(1);
@ -1344,7 +1361,7 @@ Init(const malloc_table_t* aMallocTable)
// Set defaults of things that can be affected by the $DMD env var.
gMode = Normal;
gSampleBelowSize = 1;
gSampleBelowSize = gDefaultSampleBelowSize;
// DMD is controlled by the |DMD| environment variable.
// - If it's unset or empty or "0", DMD doesn't run.
@ -1737,7 +1754,8 @@ Dump(Writer aWriter)
size_t totalUsableSize = unreportedUsableSize + reportedUsableSize;
WriteTitle("Invocation\n");
W("$DMD = '%s'\n\n", gDMDEnvVar);
W("$DMD = '%s'\n", gDMDEnvVar);
W("Sample-below size = %lld\n\n", (long long)(gSampleBelowSize));
PrintSortedGroups(aWriter, "Double-reported", "double-reported",
*gDoubleReportBlockGroupTable, kNoSize, kNoSize);
@ -1807,6 +1825,9 @@ RunTestMode(FILE* fp)
{
Writer writer(FpWrite, fp);
// The first part of this test requires sampling to be disabled.
gSampleBelowSize = 1;
// 0th Dump. Zero for everything.
Dump(writer);

4
memory/replace/dmd/test-expected.dmd
View File

@ -3,6 +3,7 @@ Invocation
------------------------------------------------------------------
$DMD = '--mode=test'
Sample-below size = 1
------------------------------------------------------------------
Double-reported blocks
@ -35,6 +36,7 @@ Invocation
------------------------------------------------------------------
$DMD = '--mode=test'
Sample-below size = 1
------------------------------------------------------------------
Double-reported blocks
@ -204,6 +206,7 @@ Invocation
------------------------------------------------------------------
$DMD = '--mode=test'
Sample-below size = 1
------------------------------------------------------------------
Double-reported blocks
@ -286,6 +289,7 @@ Invocation
------------------------------------------------------------------
$DMD = '--mode=test'
Sample-below size = 128
------------------------------------------------------------------
Double-reported blocks