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coccicheck: optionally batch spatch invocations
In our "make coccicheck" rule, we currently feed each source file to its own individual invocation of spatch. This has a few downsides: - it repeats any overhead spatch has for starting up and reading the patch file - any included header files may get processed from multiple invocations. This is slow (we see the same header files multiple times) and may produce a resulting patch with repeated hunks (which cannot be applied without further cleanup) Ideally we'd just invoke a single instance of spatch per rule-file and feed it all source files. But spatch can be rather memory hungry when run in this way. I measured the peak RSS going from ~90MB for a single file to ~1900MB for all files. Multiplied by multiple rule files being processed at the same time (for "make -j"), this can make things slower or even cause them to fail (e.g., this is reported to happen on our Travis builds). Instead, let's provide a tunable knob. We'll leave the default at "1", but it can be cranked up to "999" for maximum CPU/memory tradeoff, or people can find points in between that serve their particular machines. Here are a few numbers running a single rule via: SIZES='1 4 16 999' RULE=contrib/coccinelle/object_id.cocci for i in $SIZES; do make clean /usr/bin/time -o $i.out --format='%e | %U | %S | %M' \ make $RULE.patch SPATCH_BATCH_SIZE=$i done for i in $SIZES; do printf '%4d | %s\n' $i "$(cat $i.out)" done which yields: 1 | 97.73 | 93.38 | 4.33 | 100128 4 | 52.80 | 51.14 | 1.69 | 135204 16 | 35.82 | 35.09 | 0.76 | 284124 999 | 23.30 | 23.13 | 0.20 | 1903852 The implementation is done with xargs, which should be widely available; it's in POSIX, we rely on it already in the test suite. And "coccicheck" is really a developer-only tool anyway, so it's not a big deal if obscure systems can't run it. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
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13
Makefile
13
Makefile
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@ -1174,8 +1174,10 @@ PTHREAD_CFLAGS =
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SPARSE_FLAGS ?=
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SP_EXTRA_FLAGS =
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# For the 'coccicheck' target
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# For the 'coccicheck' target; setting SPATCH_BATCH_SIZE higher will
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# usually result in less CPU usage at the cost of higher peak memory.
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SPATCH_FLAGS = --all-includes --patch .
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SPATCH_BATCH_SIZE = 1
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include config.mak.uname
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-include config.mak.autogen
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@ -2790,12 +2792,9 @@ endif
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%.cocci.patch: %.cocci $(COCCI_SOURCES)
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@echo ' ' SPATCH $<; \
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ret=0; \
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for f in $(COCCI_SOURCES); do \
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$(SPATCH) --sp-file $< $$f $(SPATCH_FLAGS) || \
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{ ret=$$?; break; }; \
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done >$@+ 2>$@.log; \
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if test $$ret != 0; \
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if ! echo $(COCCI_SOURCES) | xargs -n $(SPATCH_BATCH_SIZE) \
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$(SPATCH) --sp-file $< $(SPATCH_FLAGS) \
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>$@+ 2>$@.log; \
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then \
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cat $@.log; \
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exit 1; \
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