On Mon, Jul 01, 2013 at 02:50:46PM +0200, Ingo Molnar wrote:
> > Yep, I didn't run -a since I wanted to trace only the build process.
> > Btw, the build-kernel.sh script looks like this:
> >
> > #!/bin/bash
> >
> > NUM_CPUS=$(cat /proc/cpuinfo | grep processor | wc -l)
> > MAKE_OPTS=-j$(($NUM_CPUS+1))
> >
> > echo 3 > /proc/sys/vm/drop_caches
> > make $MAKE_OPTS mrproper
> > make $MAKE_OPTS oldconfig
> > make $MAKE_OPTS
> > <EOF>
> >
> > Let me try your perf tracing variant.
Ok, I removed the output directory to your trace command because it was
complaining about .config missing even if I put it both in the source
tree and in defconfig-build/ so I ended up with:
perf stat --repeat 10 -a --sync --pre 'make -s clean; echo 1 >
/proc/sys/vm/drop_caches' make -s -j64 bzImage
which should be basically the same.
And yes, this way we don't see the speedup - numbers are almost the
same. Now on to find out why do I see a speedup with my way of running
the trace.
plain 3.10
==========
Performance counter stats for 'make -s -j64 bzImage' (10 runs):
960155.777354 task-clock # 7.996 CPUs utilized
( +- 0.13% ) [100.00%]
600,993 context-switches # 0.626 K/sec
( +- 0.29% ) [100.00%]
32,764 cpu-migrations # 0.034 K/sec
( +- 0.40% ) [100.00%]
25,449,932 page-faults # 0.027 M/sec
( +- 0.00% )
3,146,429,834,505 cycles # 3.277 GHz
( +- 0.12% ) [83.27%]
2,402,804,186,892 stalled-cycles-frontend # 76.37% frontend cycles idle
( +- 0.10% ) [83.30%]
1,844,806,444,182 stalled-cycles-backend # 58.63% backend cycles idle
( +- 0.16% ) [66.61%]
1,801,184,009,281 instructions # 0.57 insns per cycle
# 1.33 stalled cycles per insn
( +- 0.15% ) [83.27%]
402,482,696,262 branches # 419.185 M/sec
( +- 0.04% ) [83.58%]
17,550,736,725 branch-misses # 4.36% of all branches
( +- 0.09% ) [83.25%]
120.072676076 seconds time elapsed
( +- 0.13% )
+ patch
=======
Performance counter stats for 'make -s -j64 bzImage' (10 runs):
960212.466648 task-clock # 7.996 CPUs utilized
( +- 0.11% ) [100.00%]
600,078 context-switches # 0.625 K/sec
( +- 0.23% ) [100.00%]
32,708 cpu-migrations # 0.034 K/sec
( +- 0.51% ) [100.00%]
25,450,046 page-faults # 0.027 M/sec
( +- 0.00% )
3,141,378,247,404 cycles # 3.272 GHz
( +- 0.09% ) [83.32%]
2,398,997,896,542 stalled-cycles-frontend # 76.37% frontend cycles idle
( +- 0.16% ) [83.39%]
1,841,987,157,784 stalled-cycles-backend # 58.64% backend cycles idle
( +- 0.19% ) [66.70%]
1,798,363,791,924 instructions # 0.57 insns per cycle
# 1.33 stalled cycles per insn
( +- 0.12% ) [83.39%]
403,257,285,840 branches # 419.967 M/sec
( +- 0.07% ) [83.39%]
17,552,193,349 branch-misses # 4.35% of all branches
( +- 0.07% ) [83.20%]
120.079804432 seconds time elapsed
( +- 0.11% )
--
Regards/Gruss,
Boris.
Sent from a fat crate under my desk. Formatting is fine.
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