On Fri, 26 Aug 2016, Stuart Bennett wrote: > I reproducibly found that on initial booting, with no system load, 0x36 came > up with processors clocked at 900MHz (below the cpufreq scaling_min_freq of > 1200MHz), before then settling to 1200MHz after some time, whereas 0x32 and > 0x38 behaved alike, with the cores at much higher initial frequencies (later > settling to 1200MHz).
This matches the behavior described in https://communities.intel.com/thread/105416 for the Haswell-E i7-5820K. So, I'd say it is indeed the same microcode defect. > Using the 0x38 microcode I have not yet had any 400MHz occurrences BUT the > time 0x38 has been on test is much less. > > So, in summary, the initial signs are good that 0x38 may fix the 0x36 > performance regression, but I think a couple more weeks' use would make me > more certain of that. Stuart, thank you very much for doing all this testing. I am actually pretty sure that microcode 0x38 indeed fixed the regression, based on the behavior you described and the report for the Haswell-E i7-5820K. I will tag this issue as fixed, but I will not close the bug report yet. Should you notice the regression still exists, please send a note to the bug report... -- Henrique Holschuh
