Changeset 37919 in webkit for trunk/JavaScriptCore

Timestamp:

Oct 27, 2008, 7:40:13 PM (17 years ago)

Author:

[email protected]

Message:

2008-10-27 Geoffrey Garen <​[email protected]>

Reviewed by Maciej Stachowiak.

Stop discarding CodeBlock samples that can't be charged to a specific
opcode. Instead, charge the relevant CodeBlock, and provide a footnote
explaining the situation.

This will help us tell which CodeBlocks are hot, even if we can't
identify specific lines of code within the CodeBlocks.

• VM/SamplingTool.cpp: (JSC::ScopeSampleRecord::sample): (JSC::compareScopeSampleRecords): (JSC::SamplingTool::dump):

• VM/SamplingTool.h: (JSC::ScopeSampleRecord::ScopeSampleRecord): (JSC::ScopeSampleRecord::~ScopeSampleRecord):

Location:

trunk/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• VM/SamplingTool.cpp (modified) (7 diffs)
• VM/SamplingTool.h (modified) (2 diffs)

trunk/JavaScriptCore/ChangeLog

@@ +1 @@
+2008-10-27  Geoffrey Garen  <[email protected]>
+
+        Reviewed by Maciej Stachowiak.
+        
+        Stop discarding CodeBlock samples that can't be charged to a specific
+        opcode. Instead, charge the relevant CodeBlock, and provide a footnote
+        explaining the situation.
+        
+        This will help us tell which CodeBlocks are hot, even if we can't
+        identify specific lines of code within the CodeBlocks.
+
+        * VM/SamplingTool.cpp:
+        (JSC::ScopeSampleRecord::sample):
+        (JSC::compareScopeSampleRecords):
+        (JSC::SamplingTool::dump):
+
+        * VM/SamplingTool.h:
+        (JSC::ScopeSampleRecord::ScopeSampleRecord):
+        (JSC::ScopeSampleRecord::~ScopeSampleRecord):
+
 2008-10-27  Geoffrey Garen  <[email protected]>
 

trunk/JavaScriptCore/VM/SamplingTool.cpp

@@ -42 +42 @@
 void ScopeSampleRecord::sample(CodeBlock* codeBlock, Instruction* vPC)
 {
-    if (!m_vpcCounts) {
+    if (!m_samples) {
         m_size = codeBlock->instructions.size();
-        m_vpcCounts = static_cast<int*>(calloc(m_size, sizeof(int)));
+        m_samples = static_cast<int*>(calloc(m_size, sizeof(int)));
         m_codeBlock = codeBlock;
     }
 
-    unsigned codeOffset = vPC - codeBlock->instructions.begin();
+    ++m_sampleCount;
+
+    unsigned offest = vPC - codeBlock->instructions.begin();
     // Since we don't read and write codeBlock and vPC atomically, this check
     // can fail if we sample mid op_call / op_ret.
-    if (codeOffset < m_size) {
-        m_vpcCounts[codeOffset]++;
-        m_totalCount++;
+    if (offest < m_size) {
+        m_samples[offest]++;
+        m_opcodeSampleCount++;
     }
 }
@@ -173 +175 @@
     const ScopeSampleRecord* const rightValue = *static_cast<const ScopeSampleRecord* const *>(right);
 
-    return (leftValue->m_totalCount < rightValue->m_totalCount) ? 1 : (leftValue->m_totalCount > rightValue->m_totalCount) ? -1 : 0;
+    return (leftValue->m_sampleCount < rightValue->m_sampleCount) ? 1 : (leftValue->m_sampleCount > rightValue->m_sampleCount) ? -1 : 0;
 }
 
@@ -226 +228 @@
     printf("\tcti %% of self:\tcti count / sample count\n");
     
-    // (3) Calculate 'codeBlockSampleCount', build and sort 'codeBlockSamples' array.
+    // (3) Build and sort 'codeBlockSamples' array.
 
     int scopeCount = m_scopeSampleMap->size();
-    long long codeBlockSampleCount = 0;
     Vector<ScopeSampleRecord*> codeBlockSamples(scopeCount);
     ScopeSampleRecordMap::iterator iter = m_scopeSampleMap->begin();
-    for (int i = 0; i < scopeCount; ++i, ++iter) {
+    for (int i = 0; i < scopeCount; ++i, ++iter)
         codeBlockSamples[i] = iter->second;
-        codeBlockSampleCount += codeBlockSamples[i]->m_totalCount;
-    }
 
     qsort(codeBlockSamples.begin(), scopeCount, sizeof(ScopeSampleRecord*), compareScopeSampleRecords);
@@ -241 +240 @@
     // (4) Print data from 'codeBlockSamples' array.
 
-    printf("\nCodeBlock samples [*]\n\n"); 
+    printf("\nCodeBlock samples\n\n"); 
 
     for (int i = 0; i < scopeCount; ++i) {
@@ -247 +246 @@
         CodeBlock* codeBlock = record->m_codeBlock;
 
-        double blockPercent = (record->m_totalCount * 100.0) / codeBlockSampleCount;
+        double blockPercent = (record->m_sampleCount * 100.0) / m_sampleCount;
 
         if (blockPercent >= 1) {
             Instruction* code = codeBlock->instructions.begin();
-            printf("#%d: %s:%d: %d / %lld (%.3f%%)\n", i + 1, record->m_scope->sourceURL().UTF8String().c_str(), codeBlock->lineNumberForVPC(code), record->m_totalCount, codeBlockSampleCount, blockPercent);
+            printf("#%d: %s:%d: %d / %lld (%.3f%%)\n", i + 1, record->m_scope->sourceURL().UTF8String().c_str(), codeBlock->lineNumberForVPC(code), record->m_sampleCount, m_sampleCount, blockPercent);
             if (i < 10) {
                 HashMap<unsigned,unsigned> lineCounts;
                 codeBlock->dump(exec);
+
+                printf("    Opcode and line number samples [*]\n\n");
                 for (unsigned op = 0; op < record->m_size; ++op) {
-                    int count = record->m_vpcCounts[op];
+                    int count = record->m_samples[op];
                     if (count) {
                         printf("    [% 4d] has sample count: % 4d\n", op, count);
@@ -264 +265 @@
                 }
                 printf("\n");
+
                 int linesCount = lineCounts.size();
                 Vector<LineCountInfo> lineCountInfo(linesCount);
@@ -278 +280 @@
                 }
                 printf("\n");
+                printf("    [*] Samples inside host code are charged to the calling Opcode.\n");
+                printf("        Samples on a call / return boundary are not charged to a specific opcode or line.\n\n");
+                printf("            Samples on a call / return boundary: %d / %d (%.3f%%)\n\n", record->m_sampleCount - record->m_opcodeSampleCount, record->m_sampleCount, (static_cast<double>(record->m_sampleCount - record->m_opcodeSampleCount) * 100) / record->m_sampleCount);
             }
         }
     }
-
-    printf("\n[*] Samples inside host code are charged to the calling Opcode.\n");
-    printf("    Samples that fall on a call / return boundary are discarded.\n\n");
-    printf("\tSamples discarded:\t\t%lld / %lld (%.3f%%)\n\n", m_sampleCount - codeBlockSampleCount, m_sampleCount, (static_cast<double>(m_sampleCount - codeBlockSampleCount) * 100) / m_sampleCount);
 }
 

trunk/JavaScriptCore/VM/SamplingTool.h

@@ -46 +46 @@
 
     struct ScopeSampleRecord {
-        RefPtr<ScopeNode> m_scope;
-        CodeBlock* m_codeBlock;
-        int m_totalCount;
-        int* m_vpcCounts;
-        unsigned m_size;
-        
         ScopeSampleRecord(ScopeNode* scope)
             : m_scope(scope)
             , m_codeBlock(0)
-            , m_totalCount(0)
-            , m_vpcCounts(0)
+            , m_sampleCount(0)
+            , m_opcodeSampleCount(0)
+            , m_samples(0)
             , m_size(0)
         {
@@ -63 +58 @@
         ~ScopeSampleRecord()
         {
-            if (m_vpcCounts)
-                free(m_vpcCounts);
+            if (m_samples)
+                free(m_samples);
         }
         
         void sample(CodeBlock*, Instruction*);
+
+        RefPtr<ScopeNode> m_scope;
+        CodeBlock* m_codeBlock;
+        int m_sampleCount;
+        int m_opcodeSampleCount;
+        int* m_samples;
+        unsigned m_size;
     };