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Patch "perf header: Fixup reading of HEADER_NRCPUS feature" has been added to the 3.14-stable tree

PATCH [email protected] 1 participant 1 message Oct 13, 2015

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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 3.14-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-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From caa470475d9b59eeff093ae650800d34612c4379 Mon Sep 17 00:00:00 2001

From: Arnaldo Carvalho de Melo <[email protected]>
Date: Fri, 11 Sep 2015 12:36:12 -0300
Subject: perf header: Fixup reading of HEADER_NRCPUS feature

From: Arnaldo Carvalho de Melo <[email protected]>

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 <[email protected]>
Cc Adrian Hunter <[email protected]>
Cc Borislav Petkov <[email protected]>
Cc David Ahern <[email protected]>
Cc Frederic Weisbecker <[email protected]>
Cc Jiri Olsa <[email protected]>
Cc Kan Liang <[email protected]>
Cc Stephane Eranian <[email protected]>
Cc Wang Nan <[email protected]>
Fixes fbe96f29ce4b ("perf tools: Make perf.data more self-descriptive (v8)")
Link http://lkml.kernel.org/r/[email protected] open here
Signed-off-by Arnaldo Carvalho de Melo <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 tools/perf/util/header.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
tools/perf/util/header.c +2 -2
@@ -1715,7 +1715,7 @@ 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))

@@ -1724,7 +1724,7 @@ 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 [email protected] are

queue-3.14/perf-stat-get-correct-cpu-id-for-print_aggr.patch queue-3.14/perf-tools-fix-copying-of-proc-kcore.patch queue-3.14/perf-hists-update-the-column-width-for-the-srcline-sort-key.patch queue-3.14/perf-header-fixup-reading-of-header_nrcpus-feature.patch