Re: [BENCHMARK] 2.5.42-mm2 contest results

[Andrew Morton <akpm@digeo.com>]

Con Kolivas wrote:
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> Here are the surprisingly different results from 2.5.42-mm2 with the contest
> benchmark (http://contest.kolivas.net). This was run with pagetable sharing
> enabled. Older results hidden for clarity.
> 
> noload:
> Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
> 2.5.41-mm3 [1]          74.4    93      0       0       1.11
> 2.5.42 [2]              72.5    93      0       0       1.08
> 2.5.42-mm2 [3]          79.0    92      0       0       1.18
> 

Well something is burning CPU there, and I do not know what it is.
Things are normal here:

With 2.5.42-mm2++, shared pagetables enabled:
make -j6 bzImage  416.97s user 33.94s system 374% cpu 2:00.28 total

With 2.5.42+last night's BK:
make -j6 bzImage  416.09s user 33.04s system 370% cpu 2:01.15 total

With 2.5.42:
make -j6 bzImage  416.56s user 32.49s system 375% cpu 1:59.69 total

So.  Could you please profile the `noload' run?  Just enable oprofile
and local IO APIC and do:

- add "idle=poll" to your kernel boot commandline
- sudo rm -rf /var/lib/oprofile
- sudo op_start --vmlinux=/boot/vmlinux --ctr0-event=CPU_CLK_UNHALTED \
  --ctr0-count=600000
- time make -j4 bzImage ; sudo op_stop
- oprofpp -l -i /boot/vmlinux
- sudo killall oprofiled

(Do the `make' quickly after the op_start to avoid bogus idle time).

Thanks.