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* [PATCH] perf: disable parallelism for 'make clean'
@ 2018-07-05 13:15 Rasmus Villemoes
  2018-07-05 13:49 ` Jiri Olsa
  2018-08-23  8:37 ` [tip:perf/urgent] perf tools: Disable " tip-bot for Rasmus Villemoes
  0 siblings, 2 replies; 8+ messages in thread
From: Rasmus Villemoes @ 2018-07-05 13:15 UTC (permalink / raw)
  To: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
	Alexander Shishkin, Jiri Olsa, Namhyung Kim
  Cc: Rasmus Villemoes, linux-kernel

The Yocto build system does a 'make clean' when rebuilding due to
changed dependencies, and that consistently fails for me (causing the
whole BSP build to fail) with errors such as

| find: '[...]/perf/1.0-r9/perf-1.0/plugin_mac80211.so': No such file or directory
| find: '[...]/perf/1.0-r9/perf-1.0/plugin_mac80211.so': No such file or directory
| find: find: '[...]/perf/1.0-r9/perf-1.0/libtraceevent.a''[...]/perf/1.0-r9/perf-1.0/libtraceevent.a': No such file or directory: No such file or directory
|
[...]
| find: cannot delete '/mnt/xfs/devel/pil/yocto/tmp-glibc/work/wandboard-oe-linux-gnueabi/perf/1.0-r9/perf-1.0/util/.pstack.o.cmd': No such file or directory

Apparently (despite the comment), 'make clean' ends up launching
multiple sub-makes that all want to remove the same things - perhaps
this only happens in combination with a O=... parameter. In any case, we
don't lose much by explicitly disabling the parallelism for the clean
target, and it makes automated builds much more reliable.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
Another option is to add -ignore_readdir_race to all find commands,
but that's a lot more invasive and only works properly together with
-delete with a very recent GNU find
(https://savannah.gnu.org/bugs/?52981).

 tools/perf/Makefile | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index 225454416ed5..7902a5681fc8 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -84,10 +84,10 @@ endif # has_clean
 endif # MAKECMDGOALS
 
 #
-# The clean target is not really parallel, don't print the jobs info:
+# Explicitly disable parallelism for the clean target.
 #
 clean:
-	$(make)
+	$(make) -j1
 
 #
 # The build-test target is not really parallel, don't print the jobs info,
-- 
2.16.4


^ permalink raw reply related	[flat|nested] 8+ messages in thread
* [PATCH] perf: disable parallelism for 'make clean'
@ 2018-07-05 20:55 Rasmus Villemoes
  2018-07-05 22:18 ` Andre McCurdy
  0 siblings, 1 reply; 8+ messages in thread
From: Rasmus Villemoes @ 2018-07-05 20:55 UTC (permalink / raw)
  To: openembedded-core

Whenever perf got rebuilt, I was consistently getting errors such as

| find: '[...]/perf/1.0-r9/perf-1.0/plugin_mac80211.so': No such file or directory
| find: '[...]/perf/1.0-r9/perf-1.0/plugin_mac80211.so': No such file or directory
| find: find: '[...]/perf/1.0-r9/perf-1.0/libtraceevent.a''[...]/perf/1.0-r9/perf-1.0/libtraceevent.a': No such file or directory: No such file or directory
|
[...]
| find: cannot delete '/mnt/xfs/devel/pil/yocto/tmp-glibc/work/wandboard-oe-linux-gnueabi/perf/1.0-r9/perf-1.0/util/.pstack.o.cmd': No such file or directory

breaking the whole build. The root cause seems to be that the implicit
'make clean' done during do_configure ends up running in parallel, and
thus multiple find commands attempt to stat and/or delete the same
file.

This patch of tools/perf/Makefile has been ack'ed
upstream (lkml.kernel.org/r/20180705134955.GB3686@krava). Since the sed
script matches exactly the lines

clean:
	$(make)

it should be harmless to have this even with a fixed kernel, and it can
be removed if and when all relevant -stable kernels have it.

Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
---
 meta/recipes-kernel/perf/perf.bb | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/meta/recipes-kernel/perf/perf.bb b/meta/recipes-kernel/perf/perf.bb
index 51f5597eb9..1cf2666ee5 100644
--- a/meta/recipes-kernel/perf/perf.bb
+++ b/meta/recipes-kernel/perf/perf.bb
@@ -145,6 +145,11 @@ python copy_perf_source_from_kernel() {
             bb.utils.copyfile(src, dest)
 }
 
+do_configure[prefuncs] += "disable_clean_parallelism"
+disable_clean_parallelism () {
+	sed -i '/^clean:$/{n;s/^\t\$(make)$/\t\$(make) -j1/}' ${S}/tools/perf/Makefile
+}
+
 do_configure_prepend () {
     # If building a multlib based perf, the incorrect library path will be
     # detected by perf, since it triggers via: ifeq ($(ARCH),x86_64). In a 32 bit
-- 
2.16.4



^ permalink raw reply related	[flat|nested] 8+ messages in thread
end of thread, other threads:[~2018-08-23  8:37 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2018-07-05 13:15 [PATCH] perf: disable parallelism for 'make clean' Rasmus Villemoes
2018-07-05 13:49 ` Jiri Olsa
2018-08-15  7:30   ` Rasmus Villemoes
2018-08-15 19:33     ` Arnaldo Carvalho de Melo
2018-08-23  8:37 ` [tip:perf/urgent] perf tools: Disable " tip-bot for Rasmus Villemoes
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2018-07-05 20:55 [PATCH] perf: disable " Rasmus Villemoes
2018-07-05 22:18 ` Andre McCurdy
2018-07-06  7:26   ` Rasmus Villemoes

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