Re: scheduler / perf stat question about CPU-migrations

From: Ted Ts'o
Date: Thu Jun 16 2011 - 22:44:33 EST


On Thu, Jun 16, 2011 at 05:18:39PM +0200, Frederic Weisbecker wrote:
> The only solution is too set perf affinity itself:
>
> schedtool -a 1 -e perf stat -- e2fsck -ft /dev/funarg/kbuild

Nope, that doesn't solve the problem:

# schedtool -a 1 -e perf stat -- e2fsck -ft /dev/funarg/kbuild
e2fsck 1.41.14 (22-Dec-2010)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/funarg/kbuild: 223466/1638400 files (0.3% non-contiguous), 4915668/6553600 blocks
Memory used: 2600k/0k (1069k/1532k), time: 6.72/ 1.18/ 0.36
I/O read: 137MB, write: 1MB, rate: 20.38MB/s

Performance counter stats for 'e2fsck -ft /dev/funarg/kbuild':

1523.616797 task-clock # 0.224 CPUs utilized
7227 context-switches # 0.005 M/sec
253 CPU-migrations # 0.000 M/sec
1936 page-faults # 0.001 M/sec
4176409631 cycles # 2.741 GHz
<not counted> stalled-cycles-frontend
<not counted> stalled-cycles-backend
4828485353 instructions # 1.16 insns per cycle
877742160 branches # 576.091 M/sec
8017490 branch-misses # 0.91% of all branches

6.798746204 seconds time elapsed

Note the 253 CPU migration....

- Ted
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/