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| author | Vedant Kumar <vsk@apple.com> | 2016-07-19 01:17:20 +0000 |
|---|---|---|
| committer | Vedant Kumar <vsk@apple.com> | 2016-07-19 01:17:20 +0000 |
| commit | d91d378e3a63e93145509521a5ed404af7ea8f5d (patch) | |
| tree | 14aad7957a1c1aa3a14eef7c552ace9733dbd43a /docs/CommandGuide | |
| parent | 40a2c5247c293749c005681aba150f7ae9f0cc51 (diff) | |
Retry: [llvm-profdata] Speed up merging by using a thread pool
Add a "-j" option to llvm-profdata to control the number of threads used.
Auto-detect NumThreads when it isn't specified, and avoid spawning threads when
they wouldn't be beneficial.
I tested this patch using a raw profile produced by clang (147MB). Here is the
time taken to merge 4 copies together on my laptop:
No thread pool: 112.87s user 5.92s system 97% cpu 2:01.08 total
With 2 threads: 134.99s user 26.54s system 164% cpu 1:33.31 total
Changes since the initial commit:
- When handling odd-length inputs, call ThreadPool::wait() before merging the
last profile. Should fix a race/off-by-one (see r275937).
Differential Revision: https://reviews.llvm.org/D22438
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275938 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'docs/CommandGuide')
| -rw-r--r-- | docs/CommandGuide/llvm-profdata.rst | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/docs/CommandGuide/llvm-profdata.rst b/docs/CommandGuide/llvm-profdata.rst index f5508b5b2b8f..bae0ff7d4ce0 100644 --- a/docs/CommandGuide/llvm-profdata.rst +++ b/docs/CommandGuide/llvm-profdata.rst @@ -106,6 +106,11 @@ OPTIONS conjunction with -instr. Defaults to false, since it can inhibit compiler optimization during PGO. +.. option:: -num-threads=N, -j=N + + Use N threads to perform profile merging. When N=0, llvm-profdata auto-detects + an appropriate number of threads to use. This is the default. + EXAMPLES ^^^^^^^^ Basic Usage |