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0e2af95669
There's another source of overhead in the perf version string generator:
git update-index -q --refresh
... which will iterate the whole checked out tree. This can be pretty
slow on NFS volumes, but takes some time even with local SSD disks and a
fully cached kernel tree:
$ perf stat --null --repeat 3 --pre "rm -f PERF-VERSION-FILE" util/PERF-VERSION-GEN
PERF_VERSION = 3.7.rc3.g5399b3b.dirty
PERF_VERSION = 3.7.rc3.g5399b3b.dirty
PERF_VERSION = 3.7.rc3.g5399b3b.dirty
Performance counter stats for 'util/PERF-VERSION-GEN' (3 runs):
0.306999221 seconds time elapsed ( +- 0.56% )
So remove the .dirty differentiator as well - it adds little information
because locally patched git trees are common, but seldom are the perf
tools modified.
So a lot of version strings are reported as 'dirty' while in fact they
are pristine perf builds. For example 99% of my perf builds are not
patched but the kernel tree is slightly patched, which adds the .dirty
tag.
Eliminating that tag speeds up version generation by another order of
magnitude:
$ perf stat --null --repeat 3 --sync --pre "rm -f PERF-VERSION-FILE" util/PERF-VERSION-GEN
PERF_VERSION = 3.7.rc3.g4b0bd3
PERF_VERSION = 3.7.rc3.g4b0bd3
PERF_VERSION = 3.7.rc3.g4b0bd3
Performance counter stats for 'util/PERF-VERSION-GEN' (3 runs):
0.021270923 seconds time elapsed ( +- 1.94% )
(Also clean up some of the comments around this code.)
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Vagin <avagin@openvz.org>
Cc: Borislav Petkov <bp@amd64.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20121030085441.GC8245@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
38 lines
688 B
Bash
Executable File
38 lines
688 B
Bash
Executable File
#!/bin/sh
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if [ $# -eq 1 ] ; then
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OUTPUT=$1
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fi
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GVF=${OUTPUT}PERF-VERSION-FILE
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LF='
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'
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#
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# First check if there is a .git to get the version from git describe
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# otherwise try to get the version from the kernel Makefile
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#
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if test -d ../../.git -o -f ../../.git &&
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VN=$(echo $(git tag -l "v[0-9].[0-9]*" | tail -1)"-g"$(git log -1 --abbrev=4 --pretty=format:"%h" HEAD) 2>/dev/null)
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then
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VN=$(echo "$VN" | sed -e 's/-/./g');
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else
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VN=$(MAKEFLAGS= make -sC ../.. kernelversion)
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fi
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VN=$(expr "$VN" : v*'\(.*\)')
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if test -r $GVF
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then
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VC=$(sed -e 's/^PERF_VERSION = //' <$GVF)
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else
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VC=unset
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fi
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test "$VN" = "$VC" || {
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echo >&2 "PERF_VERSION = $VN"
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echo "PERF_VERSION = $VN" >$GVF
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}
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