This is a note to let you know that I've just added the patch titled
perf header: Fixup reading of HEADER_NRCPUS feature
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
perf-header-fixup-reading-of-header_nrcpus-feature.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From caa470475d9b59eeff093ae650800d34612c4379 Mon Sep 17 00:00:00 2001
From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Date: Fri, 11 Sep 2015 12:36:12 -0300
Subject: perf header: Fixup reading of HEADER_NRCPUS feature
From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
commit caa470475d9b59eeff093ae650800d34612c4379 upstream.
The original patch introducing this header wrote the number of CPUs available
and online in one order and then swapped those values when reading, fix it.
Before:
# perf record usleep 1
# perf report --header-only | grep 'nrcpus \(online\|avail\)'
# nrcpus online : 4
# nrcpus avail : 4
# echo 0 > /sys/devices/system/cpu/cpu2/online
# perf record usleep 1
# perf report --header-only | grep 'nrcpus \(online\|avail\)'
# nrcpus online : 4
# nrcpus avail : 3
# echo 0 > /sys/devices/system/cpu/cpu1/online
# perf record usleep 1
# perf report --header-only | grep 'nrcpus \(online\|avail\)'
# nrcpus online : 4
# nrcpus avail : 2
After the fix, bringing back the CPUs online:
# perf report --header-only | grep 'nrcpus \(online\|avail\)'
# nrcpus online : 2
# nrcpus avail : 4
# echo 1 > /sys/devices/system/cpu/cpu2/online
# perf record usleep 1
# perf report --header-only | grep 'nrcpus \(online\|avail\)'
# nrcpus online : 3
# nrcpus avail : 4
# echo 1 > /sys/devices/system/cpu/cpu1/online
# perf record usleep 1
# perf report --header-only | grep 'nrcpus \(online\|avail\)'
# nrcpus online : 4
# nrcpus avail : 4
Acked-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Kan Liang <kan.liang@xxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Fixes: fbe96f29ce4b ("perf tools: Make perf.data more self-descriptive (v8)")
Link: http://lkml.kernel.org/r/20150911153323.GP23511@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
tools/perf/util/header.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -1729,7 +1729,7 @@ static int process_nrcpus(struct perf_fi
if (ph->needs_swap)
nr = bswap_32(nr);
- ph->env.nr_cpus_online = nr;
+ ph->env.nr_cpus_avail = nr;
ret = readn(fd, &nr, sizeof(nr));
if (ret != sizeof(nr))
@@ -1738,7 +1738,7 @@ static int process_nrcpus(struct perf_fi
if (ph->needs_swap)
nr = bswap_32(nr);
- ph->env.nr_cpus_avail = nr;
+ ph->env.nr_cpus_online = nr;
return 0;
}
Patches currently in stable-queue which might be from acme@xxxxxxxxxx are
queue-3.10/perf-header-fixup-reading-of-header_nrcpus-feature.patch
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