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p5302: count up to online-cpus for thread tests

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When PERF_EXTRA is enabled, p5302 checks the performance of index-pack
with various numbers of threads. This can be useful for deciding what
the default should be (which is currently capped at 3 threads based on
the results of this script).

However, we only go up to 8 threads, and modern machines may have more.
Let's get the number of CPUs from test-tool, and test various numbers of
threads between one and that maximum.

Note that the current tests aren't all identical, as we have to set
GIT_FORCE_THREADS for the --threads=1 test (which measures the overhead
of starting a single worker thread versus the "0" case of using the main
thread). To keep the loop simple, we'll keep the "0" case out of it, and
set GIT_FORCE_THREADS=1 for all of the other cases (it's a noop for all
but the "1" case, since numbers higher than 1 would always need
threads).

Note also that we could skip running "test-tool" if PERF_EXTRA isn't
set. However, there's some small value in knowing the number of threads,
so that we can mark each test as skipped in the output.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Jeff King 2020-08-21 13:54:51 -04:00 committed by Junio C Hamano
parent 47274251a4
commit 218389b9f3
1 changed files with 24 additions and 23 deletions
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43
t/perf/p5302-pack-index.sh
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@ -13,35 +13,36 @@ test_expect_success 'repack' '
export PACK
'
# Rather than counting up and doubling each time, count down from the endpoint,
# halving each time. That ensures that our final test uses as many threads as
# CPUs, even if it isn't a power of 2.
test_expect_success 'set up thread-counting tests' '
t=$(test-tool online-cpus) &&
threads= &&
while test $t -gt 0
do
threads="$t $threads"
t=$((t / 2))
done
'
test_perf PERF_EXTRA 'index-pack 0 threads' '
rm -rf repo.git &&
git init --bare repo.git &&
GIT_DIR=repo.git git index-pack --threads=1 --stdin < $PACK
'
test_perf PERF_EXTRA 'index-pack 1 thread ' '
for t in $threads
do
THREADS=$t
export THREADS
test_perf PERF_EXTRA "index-pack $t threads" '
rm -rf repo.git &&
git init --bare repo.git &&
GIT_DIR=repo.git GIT_FORCE_THREADS=1 git index-pack --threads=1 --stdin < $PACK
'
test_perf PERF_EXTRA 'index-pack 2 threads' '
rm -rf repo.git &&
git init --bare repo.git &&
GIT_DIR=repo.git git index-pack --threads=2 --stdin < $PACK
'
test_perf PERF_EXTRA 'index-pack 4 threads' '
rm -rf repo.git &&
git init --bare repo.git &&
GIT_DIR=repo.git git index-pack --threads=4 --stdin < $PACK
'
test_perf PERF_EXTRA 'index-pack 8 threads' '
rm -rf repo.git &&
git init --bare repo.git &&
GIT_DIR=repo.git git index-pack --threads=8 --stdin < $PACK
'
GIT_DIR=repo.git GIT_FORCE_THREADS=1 \
git index-pack --threads=$THREADS --stdin <$PACK
'
done
test_perf 'index-pack default number of threads' '
rm -rf repo.git &&