RPCS3/llvm-mirror
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm-mirror.git synced 2025-01-31 12:41:49 +01:00
Code Issues Projects Releases Wiki Activity

[CSSPGO][llvm-profgen] Merge and trim profile for cold context to reduce profile size

Browse Source 
This change allows merging and trimming cold context profile in llvm-profgen to solve profile size bloat problem. Currently when the profile's total sample is below threshold(supported by a switch), it will be considered cold and merged into a base context-less profile, which will at least keep the profile quality as good as the baseline(non-cs).

For example, two input profiles:
 [main @ foo @ bar]:60
 [main @ bar]:50
Under threshold = 100, the two profiles will be merge into one with the base context, get result:
 [bar]:110

Added two switches:
`--csprof-cold-thres=<value>`: Specified the total samples threshold for a context profile to be considered cold, with 100 being the default. Any cold context profiles will be merged into context-less base profile by default.
`--csprof-keep-cold`: Force profile generation to keep cold context profiles instead of dropping them. By default, any cold context will not be written to output profile.

Results:
Though not yet evaluating it with the latest CSSPGO, our internal branch shows neutral on performance but significantly reduce the profile size. Detailed evaluation on llvm-profgen with CSSPGO will come later.

Differential Revision: https://reviews.llvm.org/D94111
This commit is contained in:
wlei 2021-01-21 09:36:32 -08:00
parent 81c0c6d2aa
commit 6ee5e73092
9 changed files with 142 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
test/tools/llvm-profgen/inline-cs-noprobe.test
View File

@ -1,4 +1,4 @@
; RUN: llvm-profgen --perfscript=%S/Inputs/inline-cs-noprobe.perfscript --binary=%S/Inputs/inline-cs-noprobe.perfbin --output=%t --show-unwinder-output | FileCheck %s --check-prefix=CHECK-UNWINDER
; RUN: llvm-profgen --perfscript=%S/Inputs/inline-cs-noprobe.perfscript --binary=%S/Inputs/inline-cs-noprobe.perfbin --output=%t --show-unwinder-output --csprof-cold-thres=0 | FileCheck %s --check-prefix=CHECK-UNWINDER
; RUN: FileCheck %s --input-file %t
; CHECK:[main:1 @ foo]:44:0

2
test/tools/llvm-profgen/inline-cs-pseudoprobe.test
View File

@ -1,4 +1,4 @@
; RUN: llvm-profgen --perfscript=%S/Inputs/inline-cs-pseudoprobe.perfscript --binary=%S/Inputs/inline-cs-pseudoprobe.perfbin --output=%t --show-unwinder-output | FileCheck %s --check-prefix=CHECK-UNWINDER
; RUN: llvm-profgen --perfscript=%S/Inputs/inline-cs-pseudoprobe.perfscript --binary=%S/Inputs/inline-cs-pseudoprobe.perfbin --output=%t --show-unwinder-output --csprof-cold-thres=0 | FileCheck %s --check-prefix=CHECK-UNWINDER
; RUN: FileCheck %s --input-file %t
; CHECK: [main:2 @ foo]:74:0

70
test/tools/llvm-profgen/merge-cold-profile.test Normal file
View File

@ -0,0 +1,70 @@
; Used the data from recursion-compression.test, refer it for the unmerged output
; RUN: llvm-profgen --perfscript=%S/Inputs/recursion-compression-pseudoprobe.perfscript --binary=%S/Inputs/recursion-compression-pseudoprobe.perfbin --output=%t --compress-recursion=-1 --csprof-cold-thres=8
; RUN: FileCheck %s --input-file %t
; Test --csprof-keep-cold
; RUN: llvm-profgen --perfscript=%S/Inputs/recursion-compression-pseudoprobe.perfscript --binary=%S/Inputs/recursion-compression-pseudoprobe.perfbin --output=%t --compress-recursion=-1 --csprof-cold-thres=100 --csprof-keep-cold
; RUN: FileCheck %s --input-file %t --check-prefix=CHECK-KEEP-COLD
; CHECK: [fa]:14:4
; CHECK-NEXT: 1: 4
; CHECK-NEXT: 3: 4
; CHECK-NEXT: 4: 2
; CHECK-NEXT: 5: 1
; CHECK-NEXT: 7: 2 fb:2
; CHECK-NEXT: 8: 1 fa:1
; CHECK-NEXT: !CFGChecksum: 120515930909
; CHECK-NEXT:[main:2 @ foo:5 @ fa:8 @ fa:7 @ fb:5 @ fb]:13:4
; CHECK-NEXT: 1: 4
; CHECK-NEXT: 2: 3
; CHECK-NEXT: 3: 1
; CHECK-NEXT: 5: 4 fb:4
; CHECK-NEXT: 6: 1 fa:1
; CHECK-NEXT: !CFGChecksum: 72617220756
; CHECK-KEEP-COLD: [fb]:19:6
; CHECK-KEEP-COLD-NEXT: 1: 6
; CHECK-KEEP-COLD-NEXT: 2: 3
; CHECK-KEEP-COLD-NEXT: 3: 3
; CHECK-KEEP-COLD-NEXT: 5: 4 fb:4
; CHECK-KEEP-COLD-NEXT: 6: 3 fa:3
; CHECK-KEEP-COLD-NEXT: !CFGChecksum: 72617220756
; CHECK-KEEP-COLD-NEXT:[fa]:14:4
; CHECK-KEEP-COLD-NEXT: 1: 4
; CHECK-KEEP-COLD-NEXT: 3: 4
; CHECK-KEEP-COLD-NEXT: 4: 2
; CHECK-KEEP-COLD-NEXT: 5: 1
; CHECK-KEEP-COLD-NEXT: 7: 2 fb:2
; CHECK-KEEP-COLD-NEXT: 8: 1 fa:1
; CHECK-KEEP-COLD-NEXT: !CFGChecksum: 120515930909
; clang -O3 -fexperimental-new-pass-manager -fuse-ld=lld -fpseudo-probe-for-profiling
; -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -Xclang -mdisable-tail-calls
; -g test.c -o a.out
; Copied from recursion-compression.test
#include <stdio.h>
int fb(int n) {
if(n > 10) return fb(n / 2);
return fa(n - 1);
}
int fa(int n) {
if(n < 2) return n;
if(n % 2) return fb(n - 1);
return fa(n - 1);
}
void foo() {
int s, i = 0;
while (i++ < 10000)
s += fa(i);
printf("sum is %d\n", s);
}
int main() {
foo();
return 0;
}

2
test/tools/llvm-profgen/noinline-cs-noprobe.test
View File

@ -1,4 +1,4 @@
; RUN: llvm-profgen --perfscript=%S/Inputs/noinline-cs-noprobe.perfscript --binary=%S/Inputs/noinline-cs-noprobe.perfbin --output=%t --show-unwinder-output | FileCheck %s --check-prefix=CHECK-UNWINDER
; RUN: llvm-profgen --perfscript=%S/Inputs/noinline-cs-noprobe.perfscript --binary=%S/Inputs/noinline-cs-noprobe.perfbin --output=%t --show-unwinder-output --csprof-cold-thres=0 | FileCheck %s --check-prefix=CHECK-UNWINDER
; RUN: FileCheck %s --input-file %t
; CHECK:[main:1 @ foo:3 @ bar]:12:3

2
test/tools/llvm-profgen/noinline-cs-pseudoprobe.test
View File

@ -1,4 +1,4 @@
; RUN: llvm-profgen --perfscript=%S/Inputs/noinline-cs-pseudoprobe.perfscript --binary=%S/Inputs/noinline-cs-pseudoprobe.perfbin --output=%t --show-unwinder-output | FileCheck %s --check-prefix=CHECK-UNWINDER
; RUN: llvm-profgen --perfscript=%S/Inputs/noinline-cs-pseudoprobe.perfscript --binary=%S/Inputs/noinline-cs-pseudoprobe.perfbin --output=%t --show-unwinder-output --csprof-cold-thres=0 | FileCheck %s --check-prefix=CHECK-UNWINDER
; RUN: FileCheck %s --input-file %t
; CHECK: [main:2 @ foo]:75:0

4
test/tools/llvm-profgen/recursion-compression-noprobe.test
View File

@ -1,7 +1,7 @@
; Firstly test uncompression(--compress-recursion=0)
; RUN: llvm-profgen --perfscript=%S/Inputs/recursion-compression-noprobe.perfscript --binary=%S/Inputs/recursion-compression-noprobe.perfbin --output=%t --compress-recursion=0
; RUN: llvm-profgen --perfscript=%S/Inputs/recursion-compression-noprobe.perfscript --binary=%S/Inputs/recursion-compression-noprobe.perfbin --output=%t --compress-recursion=0 --csprof-cold-thres=0
; RUN: FileCheck %s --input-file %t -check-prefix=CHECK-UNCOMPRESS
; RUN: llvm-profgen --perfscript=%S/Inputs/recursion-compression-noprobe.perfscript --binary=%S/Inputs/recursion-compression-noprobe.perfbin --output=%t
; RUN: llvm-profgen --perfscript=%S/Inputs/recursion-compression-noprobe.perfscript --binary=%S/Inputs/recursion-compression-noprobe.perfbin --output=%t --csprof-cold-thres=0
; RUN: FileCheck %s --input-file %t
; CHECK-UNCOMPRESS:[main:1 @ foo:3 @ fa]:14:0

4
test/tools/llvm-profgen/recursion-compression-pseudoprobe.test
View File

@ -1,7 +1,7 @@
; Firstly test uncompression(--compress-recursion=0)
; RUN: llvm-profgen --perfscript=%S/Inputs/recursion-compression-pseudoprobe.perfscript --binary=%S/Inputs/recursion-compression-pseudoprobe.perfbin --output=%t --compress-recursion=0
; RUN: llvm-profgen --perfscript=%S/Inputs/recursion-compression-pseudoprobe.perfscript --binary=%S/Inputs/recursion-compression-pseudoprobe.perfbin --output=%t --compress-recursion=0 --csprof-cold-thres=0
; RUN: FileCheck %s --input-file %t -check-prefix=CHECK-UNCOMPRESS
; RUN: llvm-profgen --perfscript=%S/Inputs/recursion-compression-pseudoprobe.perfscript --binary=%S/Inputs/recursion-compression-pseudoprobe.perfbin --output=%t --show-unwinder-output | FileCheck %s --check-prefix=CHECK-UNWINDER
; RUN: llvm-profgen --perfscript=%S/Inputs/recursion-compression-pseudoprobe.perfscript --binary=%S/Inputs/recursion-compression-pseudoprobe.perfbin --output=%t --show-unwinder-output --csprof-cold-thres=0 | FileCheck %s --check-prefix=CHECK-UNWINDER
; RUN: FileCheck %s --input-file %t
; CHECK-UNCOMPRESS: [main:2 @ foo:5 @ fa:8 @ fa:7 @ fb:5 @ fb:5 @ fb:5 @ fb:5 @ fb:5 @ fb:5 @ fb:5 @ fb:5 @ fb:6 @ fa:8 @ fa:7 @ fb:6 @ fa]:4:1

57
tools/llvm-profgen/ProfileGenerator.cpp
View File

@ -29,6 +29,19 @@ static cl::opt<int32_t, true> RecursionCompression(
cl::Hidden,
cl::location(llvm::sampleprof::CSProfileGenerator::MaxCompressionSize));
static cl::opt<uint64_t> CSProfColdThres(
"csprof-cold-thres", cl::init(100), cl::ZeroOrMore,
cl::desc("Specify the total samples threshold for a context profile to "
"be considered cold, any cold profiles will be merged into "
"context-less base profiles"));
static cl::opt<bool> CSProfKeepCold(
"csprof-keep-cold", cl::init(false), cl::ZeroOrMore,
cl::desc("This works together with --csprof-cold-thres. If the total count "
"of the profile after all merge is done is still smaller than the "
"csprof-cold-thres, it will be trimmed unless csprof-keep-cold "
"flag is specified."));
using namespace llvm;
using namespace sampleprof;
@ -68,6 +81,7 @@ void ProfileGenerator::write() {
if (std::error_code EC = WriterOrErr.getError())
exitWithError(EC, OutputFilename);
auto Writer = std::move(WriterOrErr.get());
mergeAndTrimColdProfile(ProfileMap);
Writer->write(ProfileMap);
}
@ -329,6 +343,49 @@ void CSProfileGenerator::populateInferredFunctionSamples() {
}
}
void CSProfileGenerator::mergeAndTrimColdProfile(
StringMap<FunctionSamples> &ProfileMap) {
// Nothing to merge if sample threshold is zero
if (!CSProfColdThres)
return;
// Filter the cold profiles from ProfileMap and move them into a tmp
// container
std::vector<std::pair<StringRef, const FunctionSamples *>> ToRemoveVec;
for (const auto &I : ProfileMap) {
const FunctionSamples &FunctionProfile = I.second;
if (FunctionProfile.getTotalSamples() >= CSProfColdThres)
continue;
ToRemoveVec.emplace_back(I.getKey(), &I.second);
}
// Remove the code profile from ProfileMap and merge them into BaseProileMap
StringMap<FunctionSamples> BaseProfileMap;
for (const auto &I : ToRemoveVec) {
auto Ret =
BaseProfileMap.try_emplace(I.second->getName(), FunctionSamples());
FunctionSamples &BaseProfile = Ret.first->second;
BaseProfile.merge(*I.second);
ProfileMap.erase(I.first);
}
// Merge the base profiles into ProfileMap;
for (const auto &I : BaseProfileMap) {
// Filter the cold base profile
if (!CSProfKeepCold && I.second.getTotalSamples() < CSProfColdThres &&
ProfileMap.find(I.getKey()) == ProfileMap.end())
continue;
// Merge the profile if the original profile exists, otherwise just insert
// as a new profile
FunctionSamples &OrigProfile = getFunctionProfileForContext(I.getKey());
StringRef TmpName = OrigProfile.getName();
OrigProfile.merge(I.second);
// Should use the name ref from ProfileMap's key to avoid name being freed
// from BaseProfileMap
OrigProfile.setName(TmpName);
}
}
// Helper function to extract context prefix string stack
// Extract context stack for reusing, leaf context stack will
// be added compressed while looking up function profile

8
tools/llvm-profgen/ProfileGenerator.h
View File

@ -28,7 +28,10 @@ public:
create(const BinarySampleCounterMap &BinarySampleCounters,
enum PerfScriptType SampleType);
virtual void generateProfile() = 0;
// Merge and trim profile with cold context before serialization,
// only eligible for CS profile
virtual void
mergeAndTrimColdProfile(StringMap<FunctionSamples> &ProfileMap){};
// Use SampleProfileWriter to serialize profile map
void write();
@ -200,6 +203,9 @@ public:
protected:
// Lookup or create FunctionSamples for the context
FunctionSamples &getFunctionProfileForContext(StringRef ContextId);
// Merge cold context profile whose total sample is below threshold
// into base profile.
void mergeAndTrimColdProfile(StringMap<FunctionSamples> &ProfileMap) override;
private:
// Helper function for updating body sample for a leaf location in