From mboxrd@z Thu Jan 1 00:00:00 1970 From: joshiiitr@gmail.com (Joshi) Date: Tue, 11 Sep 2018 00:02:25 +0530 Subject: CPU frequency variations Message-ID: While doing some I/O polling related experiments/optimization, I felt the need to eliminate fluctuations (in I/O performance) caused by CPU frequency variations. During benchmarks (and I mean storage ones), in order to keep running CPU at nearly constant high frequency, I tried things such as - performance governor, bios-based performance settings, explicit setting of sysfs cpu scaling max counters, kernel parameters to disable cpufreq etc. Some of above helped; On machines with less number of CPUs. While nothing seems to help on relatively heavyweight machines. Such as on this- Intel Xeon E5-2690 v3 @2.6 GHz, 2 NUMA nodes, 24 cpus each. Often storage-benchmark seem to suffer because there are more number of CPUs available; Binding it to single/few CPUs help in seeing better numbers. May I know how you deal with CPU frequency variations during benchmarks. Thanks, -- Joshi