From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shilpasri G Bhat Subject: Re: [RFC PATCH] Increase in idle power with schedutil Date: Fri, 20 May 2016 17:53:41 +0530 Message-ID: <573F01CD.6030107@linux.vnet.ibm.com> References: <1463576020-18597-1-git-send-email-shilpa.bhat@linux.vnet.ibm.com> <20160519114029.GW3193@twins.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <20160519114029.GW3193@twins.programming.kicks-ass.net> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+glppe-linuxppc-embedded-2=m.gmane.org@lists.ozlabs.org Sender: "Linuxppc-dev" To: Peter Zijlstra Cc: "Gautham R. Shenoy" , "linux-pm@vger.kernel.org" , shreyas@linux.vnet.ibm.com, "Rafael J. Wysocki" , Linux Kernel Mailing List , linuxppc-dev@ozlabs.org, Steve Muckle , Viresh Kumar , akshay.adiga@linux.vnet.ibm.com List-Id: linux-pm@vger.kernel.org SGksCgpPbiAwNS8xOS8yMDE2IDA1OjEwIFBNLCBQZXRlciBaaWpsc3RyYSB3cm90ZToKPiBPbiBX ZWQsIE1heSAxOCwgMjAxNiBhdCAxMToxMTo1MVBNICswMjAwLCBSYWZhZWwgSi4gV3lzb2NraSB3 cm90ZToKPj4gT24gV2VkLCBNYXkgMTgsIDIwMTYgYXQgMjo1MyBQTSwgU2hpbHBhc3JpIEcgQmhh dAo+PiA8c2hpbHBhLmJoYXRAbGludXgudm5ldC5pYm0uY29tPiB3cm90ZToKPj4+IFRoaXMgcGF0 Y2ggYWRkcyBkcml2ZXIgY2FsbGJhY2sgZm9yIGZhc3Rfc3dpdGNoIGFuZCBiZWxvdyBvYnNlcnZh dGlvbnMKPj4+IG9uIHNjaGVkdXRpbCBnb3Zlcm5vciBhcmUgZG9uZSB3aXRoIHRoaXMgcGF0Y2gu Cj4+Pgo+Pj4gSW4gUE9XRVI4IHRoZXJlIGlzIGEgcmVncmVzc2lvbiBvYnNlcnZlZCB3aXRoIHNj aGVkdXRpbCBjb21wYXJlZCB0bwo+Pj4gb25kZW1hbmQuIFdpdGggc2NoZWR1dGlsIHRoZSBmcmVx dWVuY3kgaXMgbm90IHJhbXBpbmcgZG93biBhbmQgaXMKPj4+IG1vc3RseSBzdHVjayBhdCBtYXgg ZnJlcXVlbmN5IGR1cmluZyBpZGxlIC4gVGhpcyBpcyBiZWNhdXNlIG9mIHRoZQo+Pj4gd2F0Y2hk b2cgdGltZXIsIGFuIFJUIHRhc2sgd2hpY2ggaXMgZmlyZWQgZXZlcnkgNCBzZWNvbmRzIHdoaWNo Cj4+PiByZXN1bHRzIGluIHJlcXVlc3RpbmcgbWF4IGZyZXF1ZW5jeS4KPj4KPj4gV2VsbCwgeWVz LCB0aGF0IHdvdWxkIGJlIHByb2JsZW1hdGljLgo+Pgo+IAo+IFJpZ2h0OyB3ZSBuZWVkIHRvIGNv bWUgdXAgd2l0aCBzb21ldGhpbmcgZm9yIFJUIHRhc2tzOyBidXQgd2hhdCBoYXBwZW5zCj4gaWYg eW91IGRpc2FibGUgdGhlIHdhdGNoZG9nPyBUaGlzIHNob3VsZCBiZSBlbnRpcmVseSBkb2FibGUg YW5kIG1pZ2h0Cj4gZ2l2ZSBhIGJldHRlciBjb21wYXJpc29uLgo+IAoKQmVsb3cgYXJlIHRoZSBj b21wYXJpc29ucyBieSBkaXNhYmxpbmcgd2F0Y2hkb2cuCkJvdGggc2NoZWR1dGlsIGFuZCBvbmRl bWFuZCBoYXZlIGEgc2ltaWxhciByYW1wLWRvd24gdHJlbmQuIEFuZCBpbiBib3RoIHRoZQpjYXNl cyBJIGNhbiBzZWUgdGhhdCBmcmVxdWVuY3kgb2YgdGhlIGNwdSBpcyBub3QgcmVkdWNlZCBpbiBk ZXRlcm1pbmlzdGljCmZhc2hpb24uIEluIGEgb2JzZXJ2YXRpb24gd2luZG93IG9mIDMwIHNlY29u ZHMgYWZ0ZXIgcnVubmluZyBhIHdvcmtsb2FkIEkgY2FuCnNlZSB0aGF0IHRoZSBmcmVxdWVuY3kg aXMgbm90IHJhbXBlZCBkb3duIG9uIHNvbWUgY3B1cyBpbiB0aGUgc3lzdGVtIGFuZCBhcmUKaWRs aW5nIGF0IG1heCBmcmVxdWVuY3kuCgpCZWxvdyBhcmUgdGhlIHNhbXBsZSB0cmFjZSBzaG93Y2Fz aW5nIHRoZSBmcmVxdWVuY3kgcmVxdWVzdCB3aGVuIHRoZSBjcHUgZW50ZXJzCmlkbGUgd2l0aCBz Y2hlZHV0aWwuCjwuLi4+LTM1MjggIDc2NTAuMDExMDEwOiBjcHVfZnJlcXVlbmN5OiBzdGF0ZT00 MzIyMDAwIGNwdV9pZD0xMjAKPC4uLj4tMzUyOCAgNzY1MC4wMjc1NDA6IHNjaGVkX3N3aXRjaDog cHJldl9jb21tPXBwYzY0X2NwdSBwcmV2X3N0YXRlPXggPT0+CgkJCW5leHRfY29tbT1zd2FwcGVy LzEyMAo8aWRsZT4tMCAgICA3NjUwLjAzNTAxNzogY3B1X2ZyZXF1ZW5jeTogc3RhdGU9NDMyMjAw MCBjcHVfaWQ9MTIwCjxpZGxlPi0wICAgIDc3MjkuNjgzNTM2OiBjcHVfZnJlcXVlbmN5OiBzdGF0 ZT00MzIyMDAwIGNwdV9pZD0xMjAKPGlkbGU+LTAgICAgNzcyOS42ODM1NTI6IHNjaGVkX3N3aXRj aDogcHJldl9jb21tPXN3YXBwZXIvMTIwIHByZXZfc3RhdGU9UiA9PT4KCQkJbmV4dF9jb21tPWt3 b3JrZXIvMTIwOjEKa3dvcmtlci8xMjAgIDc3MjkuNjgzNTY1OiBzY2hlZF9zd2l0Y2g6IHByZXZf Y29tbT1rd29ya2VyLzEyMDoxIHByZXZfc3RhdGU9UyA9PT4KCQkJIG5leHRfY29tbT1zd2FwcGVy LzEyMAoKSG93ZXZlciBvbmRlbWFuZCBnb3Zlcm5vcih3aXRoIHdhdGNoZG9nIGVuYWJsZWQpIGJl bmVmaXRzIGZyb20gdGhlIG5vaXNlIGNyZWF0ZWQKYnkgd2F0Y2hkb2cgdGltZXIgYW5kIGlzIGFi bGUgdG8gYnJpZyBkb3duIHRoZSBmcmVxdWVuY3kuCgpUaGFua3MgYW5kIFJlZ2FyZHMsClNoaWxw YQoKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KTGludXhw cGMtZGV2IG1haWxpbmcgbGlzdApMaW51eHBwYy1kZXZAbGlzdHMub3psYWJzLm9yZwpodHRwczov L2xpc3RzLm96bGFicy5vcmcvbGlzdGluZm8vbGludXhwcGMtZGV2 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [103.22.144.67]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3rB6YS1FMBzDqCd for ; Fri, 20 May 2016 22:23:56 +1000 (AEST) Received: from e28smtp08.in.ibm.com (e28smtp08.in.ibm.com [125.16.236.8]) (using TLSv1.2 with cipher CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3rB6YR2n1Zz9t43 for ; Fri, 20 May 2016 22:23:55 +1000 (AEST) Received: from localhost by e28smtp08.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 20 May 2016 17:53:51 +0530 Received: from d28relay01.in.ibm.com (d28relay01.in.ibm.com [9.184.220.58]) by d28dlp01.in.ibm.com (Postfix) with ESMTP id CE342E0040 for ; Fri, 20 May 2016 17:57:01 +0530 (IST) Received: from d28av04.in.ibm.com (d28av04.in.ibm.com [9.184.220.66]) by d28relay01.in.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u4KCNlYK54395038 for ; Fri, 20 May 2016 17:53:47 +0530 Received: from d28av04.in.ibm.com (localhost [127.0.0.1]) by d28av04.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u4KCNiA5028423 for ; Fri, 20 May 2016 17:53:46 +0530 Message-ID: <573F01CD.6030107@linux.vnet.ibm.com> Date: Fri, 20 May 2016 17:53:41 +0530 From: Shilpasri G Bhat MIME-Version: 1.0 To: Peter Zijlstra CC: "Rafael J. Wysocki" , Viresh Kumar , "linux-pm@vger.kernel.org" , Linux Kernel Mailing List , "Gautham R. Shenoy" , shreyas@linux.vnet.ibm.com, akshay.adiga@linux.vnet.ibm.com, linuxppc-dev@ozlabs.org, Steve Muckle Subject: Re: [RFC PATCH] Increase in idle power with schedutil References: <1463576020-18597-1-git-send-email-shilpa.bhat@linux.vnet.ibm.com> <20160519114029.GW3193@twins.programming.kicks-ass.net> In-Reply-To: <20160519114029.GW3193@twins.programming.kicks-ass.net> Content-Type: text/plain; charset=windows-1252 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi, On 05/19/2016 05:10 PM, Peter Zijlstra wrote: > On Wed, May 18, 2016 at 11:11:51PM +0200, Rafael J. Wysocki wrote: >> On Wed, May 18, 2016 at 2:53 PM, Shilpasri G Bhat >> wrote: >>> This patch adds driver callback for fast_switch and below observations >>> on schedutil governor are done with this patch. >>> >>> In POWER8 there is a regression observed with schedutil compared to >>> ondemand. With schedutil the frequency is not ramping down and is >>> mostly stuck at max frequency during idle . This is because of the >>> watchdog timer, an RT task which is fired every 4 seconds which >>> results in requesting max frequency. >> >> Well, yes, that would be problematic. >> > > Right; we need to come up with something for RT tasks; but what happens > if you disable the watchdog? This should be entirely doable and might > give a better comparison. > Below are the comparisons by disabling watchdog. Both schedutil and ondemand have a similar ramp-down trend. And in both the cases I can see that frequency of the cpu is not reduced in deterministic fashion. In a observation window of 30 seconds after running a workload I can see that the frequency is not ramped down on some cpus in the system and are idling at max frequency. Below are the sample trace showcasing the frequency request when the cpu enters idle with schedutil. <...>-3528 7650.011010: cpu_frequency: state=4322000 cpu_id=120 <...>-3528 7650.027540: sched_switch: prev_comm=ppc64_cpu prev_state=x ==> next_comm=swapper/120 -0 7650.035017: cpu_frequency: state=4322000 cpu_id=120 -0 7729.683536: cpu_frequency: state=4322000 cpu_id=120 -0 7729.683552: sched_switch: prev_comm=swapper/120 prev_state=R ==> next_comm=kworker/120:1 kworker/120 7729.683565: sched_switch: prev_comm=kworker/120:1 prev_state=S ==> next_comm=swapper/120 However ondemand governor(with watchdog enabled) benefits from the noise created by watchdog timer and is able to brig down the frequency. Thanks and Regards, Shilpa