* Martin Wilck <[EMAIL PROTECTED]> [2008-02-25 15:42:13]: > Hello, > > we recently did SPECpower benchmark measurements on a 2xQuad-Core > Harpertown (Intel E5440) Server and found that the results were > generally slightly better under Windows than under Linux, despite Linux > technology like the tickless kernel. The reason was twofold: > > 1 The raw performance value under Windows is 1-2% better. This seems to > be a matter of optimization of the JVM used (BEA), not a lot we can do > about it. > > 2 The power consumption under Linux at 100% and 0% load is approx. the > same as under Windows. But in the intermediate levels 50%-10%, Windows > is roughly 3-5W better (increasing towards lower load levels). This > suggests that Windows power management is more aggressive than Linux. Is > there a description somewhere how to modify cpuidle governor tunables? > > The kernel used was Fedora Rawhide 2.6.24-fc9 (x86_64). We are about to > upgrade to an even more recent kernel. The "menu" cpuidle governor was used. > > For those who don't know the SPECpower benchmark: It uses a Java-based > database-type load which runs entirely in system memory (no disk IO). > First a maximum load is calibrated. After that, the load is reduced in > steps of 10%. A final "active idle" measurement has the JVM loaded, but > no requests. > > We'd be thankful for any suggestions wrt choice of the kernel, tunables, > and other hints, which hel us to improve the Linux results.
Hi Martin, Some comparison points that come to my mind are: * Did Linux exploit all the P-States available * Whats the P-State and C-State usage at various loads * PowerTop may provide some clue Tunable: echo 1 > /sys/devices/system/cpu/sched_mc_power_savings Please check if CONFIG_SCHED_MC=y in the kernel among other power management related options like CONFIG_TICK_ONESHOT=y CONFIG_NO_HZ=y CONFIG_HIGH_RES_TIMERS=y I am trying to play with these tunables and bring down the idle power. --Vaidy _______________________________________________ Discuss mailing list [email protected] http://mail.lesswatts.org/mailman/listinfo/discuss
