MAEDA Naoaki wrote: > Peter Williams wrote: > >> 4. Overhead Measurements. To measure the implications for overhead >> introduced by these patches kernbench was used on a dual 500Mhz >> Centrino SMP system. Runs were done for a kernel without these >> patches applied, one with the patches applied but no caps being used >> and one with the patches applied and running kernbench with a soft cap >> of zero (which would be inherited by all its children). >> >> Average Optimal -j 8 Load Run: >> >> Vanilla Patch Applied Soft Cap 0% >> >> Elapsed Time 1056.1 (1.92) 1048.2 (0.62) 1064.1 (1.59) >> User Time 1908.1 (1.09) 1895.2 (1.30) 1926.6 (1.39) >> System Time 181.7 (0.60) 177.5 (0.74) 173.8 (1.07) >> Percent CPU 197.6 (0.55) 197.0 (0) 197.0 (0) >> Context Switches 49253.6 (136.31) 48881.4 (92.03) 92490.8 (163.71) >> Sleeps 28038.8 (228.11) 28136.0 (250.65) 25769.4 (280.40) > > I tried to run kernbench with hard cap, and then it spent a very > long time on "Cleaning souce tree..." phase. Because this phase > is not CPU hog, my expectation is that it act as without cap. > > That can be reproduced by just running "make clean" on top of a > kernel source tree with hard cap. > > % /usr/bin/time make clean > 1.62user 0.29system 0:01.90elapsed 101%CPU (0avgtext+0avgdata > 0maxresident)k > 0inputs+0outputs (0major+68539minor)pagefaults 0swaps > > # Without cap, it returns almost immediately > > % ~/withcap.sh -C 900 /usr/bin/time make clean > 1.61user 0.29system 1:26.17elapsed 2%CPU (0avgtext+0avgdata 0maxresident)k > 0inputs+0outputs (0major+68537minor)pagefaults 0swaps > > # With 90% hard cap, it takes about 1.5 minutes.
This is harder capping than I would expect. I'll look into probable causes. It could be caused by the simplification I made to the calculation of sinbin time. > > % ~/withcap.sh -C 100 /usr/bin/time make clean > 1.64user 0.34system 3:31.48elapsed 0%CPU (0avgtext+0avgdata 0maxresident)k > 0inputs+0outputs (0major+68538minor)pagefaults 0swaps > > # It became worse with 10% hard cap. And so it should. > > % ~/withcap.sh -c 900 /usr/bin/time make clean > 1.63user 0.28system 0:01.89elapsed 100%CPU (0avgtext+0avgdata > 0maxresident)k > 0inputs+0outputs (0major+68537minor)pagefaults 0swaps > > # It doesn't happen with soft cap. That's because soft caps allow you to go over the cap if no other tasks want the CPU. Thanks for the feedback, Peter -- Peter Williams [EMAIL PROTECTED] "Learning, n. The kind of ignorance distinguishing the studious." -- Ambrose Bierce _______________________________________________ ckrm-tech mailing list https://lists.sourceforge.net/lists/listinfo/ckrm-tech
