Arnd Bergmann wrote: > On Tuesday 15 July 2008, Rune Torgersen wrote: >> Using arch/ppc I got a 2.6.25 kernel to boot, and the kernel compile >> test I did is almost identical (within 1%) of what the arch/powerpc >> 2.6.25 did, so it seems to be a difference between 2.6.18 and 2.6.25 >> (I'll see if I can find an exact version, as I think my ppc port can >> be compiled for all versions from 2.6.18 to 25) > > You probably already know git-bisect, but if you don't, you should > definitely give it a try. It's the best tool to find which patch > exactly broke your performance.
Turns out the story is no so simple. I redid the test wih all versions of arch/ppc from 2.6.18 to 2.6.26, and also arch/powerpc (2.6.24 and 25, 26 doesn't compile because of binutil issues) This time I made very sure that the tests were performed the same way, and I made a tabel showing relative performance: kernel compile time rel context switch rel v2.6.18 01:13:33.70 1.00 7.2 1.00 v2.6.19 01:13:29.21 1.00 7.1 0.99 v2.6.20 01:13:29.58 1.00 2.8 0.39 v2.6.21 01:13:24.91 1.00 8.1 1.13 v2.6.22 01:13:42.72 1.00 4.5 0.63 v2.6.23 01:15:16.43 1.02 17 2.36 v2.6.24 01:15:30.90 1.03 20 2.78 v2.6.25 01:14:51.21 1.02 21 2.92 v2.6.26 01:14:34.76 1.01 23.8 3.31 v2.6.24-powerpc 01:17:41.99 1.06 25.8 3.58 v2.6.25-powerpc 01:18:10.10 1.06 35.7 4.96 This shows that arch/ppc no matter versin is fairly consistent in speed. Arch/powerpc is roughtly 6% worse. The contect swith column is found running lat_ctx 2 from lmbench3, and should be in microsecs. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
