From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751758AbeCTRPo (ORCPT ); Tue, 20 Mar 2018 13:15:44 -0400 Received: from cmta19.telus.net ([209.171.16.92]:47173 "EHLO cmta19.telus.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751712AbeCTRPf (ORCPT ); Tue, 20 Mar 2018 13:15:35 -0400 X-Authority-Analysis: v=2.2 cv=TI+qcxta c=1 sm=1 tr=0 a=zJWegnE7BH9C0Gl4FFgQyA==:117 a=zJWegnE7BH9C0Gl4FFgQyA==:17 a=Pyq9K9CWowscuQLKlpiwfMBGOR0=:19 a=IkcTkHD0fZMA:10 a=FGbulvE0AAAA:8 a=uj-1fHUxuGTMDH-9HfUA:9 a=QEXdDO2ut3YA:10 a=svzTaB3SJmTkU8mK-ULk:22 From: "Doug Smythies" To: "'Thomas Ilsche'" Cc: "'Linux PM'" , "'Frederic Weisbecker'" , "'Thomas Gleixner'" , "'Paul McKenney'" , "'Rik van Riel'" , "'Aubrey Li'" , "'Mike Galbraith'" , "'LKML'" , "'Peter Zijlstra'" , "'Rafael J. Wysocki'" , "Doug Smythies" References: <2142751.3U6XgWyF8u@aspire.rjw.lan> <001a01d3be0a$ad3a0ed0$07ae2c70$@net> <2043615.lCdO10SMaB@aspire.rjw.lan> yE6GempwD1KonyE6LeVquN In-Reply-To: yE6GempwD1KonyE6LeVquN Subject: RE: [RFT][PATCH v5 0/7] sched/cpuidle: Idle loop rework Date: Tue, 20 Mar 2018 10:15:30 -0700 Message-ID: <002501d3c06f$0e7cf750$2b76e5f0$@net> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Office Outlook 12.0 Content-Language: en-ca Thread-Index: AdPAMpe1b6+HMVjHQca/VUhSciawKgAMka3g X-CMAE-Envelope: MS4wfBnioFIIO9ayFtzJGFJ5cMUvtewIaA1UaGQPxLZWngAuakH09cpuhEiSlCczu/fL9uxn0B/s5DerAV33Fo1y30LIzvAT8aFeOmCBEX8p6XRW/2RC0Fsv agdfw+9keYHTJGlmTEPu54nPH0hJ6DUFwr3g5q4M9kTJYQcQGQNEerOE9dQEPWBkioiQ1ZkyVDDhPOQsRpBWO7jmtp7hpw1+w4l/uCRNhTox7jnHsk4H3kty vhBx4/CtfNxP+Fyp+JxKKaE2z86U4t+o/vCWkBFVjbbPtC5tvW5Xu4D62MyWzmTOQLgNij0Di7fMtW6bXUy/kdO4XlkWUcxHAwVv4Cxo9v2vPny4jzh6AI3o 5/YnHCwTyxNuM3UmDPSFHkVMxPndAMwybYmJQYGYyHmRKOXZx0OMlltiOU1g7ndoXfohnQBG7xqdz2e5dLZzIGE7DSqQUbOt0FweTTtHI1pgR/JYUjerHDen cDPFQmYZ5kPH9uIHv9KNHzT3LcXEjpx/SJixwMpK1O0siQNZ7BBcmr3+QzQ= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018.03.20 03:02 Thomas Ilsche wrote: ...[snip]... > Consider the Skylake server system which has residencies in C1E of > 20 us and C6 of 800 us. I use a small while(1) {usleep(300);} > unsynchronized pinned to each core. While this is an artificial > case, it is a very innocent one - easy to predict and regular. Between > vanilla 4.16.0-rc5 and idle-loop/v6, the power consumption increases > from 149.7 W to 158.1 W. On 4.16.0-rc5, the cores sleep almost > entirely in C1E. With the patches applied, the cores spend ~75% of > their sleep time in C6, ~25% in C1E. The average time/usage for C1E is > also lower with v6 at ~350 us rather than the ~550 us in C6 (and in > C1E with the baseline). Generally the new menu governor seems to chose > C1E if the next timer is an enabled sched timer - which occasionally > interrupts the sleep-interval into two C1E sleeps rather than one C6. > > Manually disabling C6, reduces power consumption back to 149.5 W. ...[snip]... Note that one of the tests that I normally do is a work/sleep frequency sweep from 100 to 2100 Hz, typically at a lowish workload. I didn't notice anything odd with this test: http://fast.smythies.com/rjw_freq_sweep.png However, your test is at 3333 Hz (well, minus overheads). I did the same as you. And was surprised to confirm your power findings. In my case package power goes from ~8.6 watts to ~7.3 watts with idle state 4 (C6) disabled. I am getting different residency times than you though. I also observe different overheads between idle state 4 being disabled or not. i.e. my actual loop frequency drops from ~2801 Hz to ~2754 Hz. Example residencies over the previous minute: Idle state 4 (C6) disabled (seconds): Idle state 0: 0.001119 Idle state 1: 0.056638 Idle state 2: 13.100550 Idle state 3: 446.266744 Idle state 4: 0.000000 Idle state 4 (C6) enabled (seconds): Idle state 0: 0.034502 Idle state 1: 1.949595 Idle state 2: 78.291793 Idle state 3: 96.467974 Idle state 4: 286.247524 ... Doug