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[BOLT] Parallelize legacy profile merging

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Merging profiles is quite expensive, but easily paralleizable.

8359 profiles on n2d-standard-128:
single-thread: 808s
multi-thread: 200s (~75% speed up)

Differential Revision: https://reviews.llvm.org/D149014
This commit is contained in:
Yi Kong
2023-03-31 17:08:16 +08:00
parent fb1ecab023
commit 35af20d9e0
1 changed files with 47 additions and 22 deletions
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69
bolt/tools/merge-fdata/merge-fdata.cpp
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@@ -20,6 +20,8 @@
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/PrettyStackTrace.h"
#include "llvm/Support/Signals.h"
#include "llvm/Support/ThreadPool.h"
#include <mutex>
#include <unordered_map>
using namespace llvm;
@@ -258,31 +260,38 @@ bool isYAML(const StringRef Filename) {
void mergeLegacyProfiles(const SmallVectorImpl<std::string> &Filenames) {
errs() << "Using legacy profile format.\n";
std::optional<bool> BoltedCollection;
StringMap<uint64_t> Entries;
for (const std::string &Filename : Filenames) {
std::mutex BoltedCollectionMutex;
typedef StringMap<uint64_t> ProfileTy;
auto ParseProfile = [&](const std::string &Filename, auto &Profiles) {
const llvm::thread::id tid = llvm::this_thread::get_id();
if (isYAML(Filename))
report_error(Filename, "cannot mix YAML and legacy formats");
ErrorOr<std::unique_ptr<MemoryBuffer>> MB =
MemoryBuffer::getFileOrSTDIN(Filename);
if (std::error_code EC = MB.getError())
report_error(Filename, EC);
errs() << "Merging data from " << Filename << "...\n";
StringRef Buf = MB.get()->getBuffer();
// Check if the string "boltedcollection" is in the first line
if (Buf.startswith("boltedcollection\n")) {
if (!BoltedCollection.value_or(true))
report_error(
Filename,
"cannot mix profile collected in BOLT and non-BOLT deployments");
BoltedCollection = true;
Buf = Buf.drop_front(17);
} else {
if (BoltedCollection.value_or(false))
report_error(
Filename,
"cannot mix profile collected in BOLT and non-BOLT deployments");
BoltedCollection = false;
{
std::lock_guard<std::mutex> Lock(BoltedCollectionMutex);
// Check if the string "boltedcollection" is in the first line
if (Buf.startswith("boltedcollection\n")) {
if (!BoltedCollection.value_or(true))
report_error(
Filename,
"cannot mix profile collected in BOLT and non-BOLT deployments");
BoltedCollection = true;
Buf = Buf.drop_front(17);
} else {
if (BoltedCollection.value_or(false))
report_error(
Filename,
"cannot mix profile collected in BOLT and non-BOLT deployments");
BoltedCollection = false;
}
}
SmallVector<StringRef> Lines;
@@ -295,15 +304,31 @@ void mergeLegacyProfiles(const SmallVectorImpl<std::string> &Filenames) {
uint64_t Count;
if (Line.substr(Pos + 1, Line.size() - Pos).getAsInteger(10, Count))
report_error(Filename, "Malformed / corrupted profile counter");
Count += Entries.lookup(Signature);
Entries.insert_or_assign(Signature, Count);
Count += Profiles[tid].lookup(Signature);
Profiles[tid].insert_or_assign(Signature, Count);
}
};
// The final reduction has non-trivial cost, make sure each thread has at
// least 4 tasks.
ThreadPoolStrategy S = optimal_concurrency(Filenames.size() / 4);
ThreadPool Pool(S);
DenseMap<llvm::thread::id, ProfileTy> ParsedProfiles(Pool.getThreadCount());
for (const auto &Filename : Filenames)
Pool.async(ParseProfile, std::cref(Filename), std::ref(ParsedProfiles));
Pool.wait();
ProfileTy MergedProfile;
for (const auto &[Thread, Profile] : ParsedProfiles)
for (const auto &[Key, Value] : Profile) {
uint64_t Count = MergedProfile.lookup(Key) + Value;
MergedProfile.insert_or_assign(Key, Count);
}
}
if (BoltedCollection)
output() << "boltedcollection\n";
for (const auto &Entry : Entries)
output() << Entry.getKey() << " " << Entry.getValue() << "\n";
for (const auto &[Key, Value] : MergedProfile)
output() << Key << " " << Value << "\n";
errs() << "Profile from " << Filenames.size() << " files merged.\n";
}