Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751868Ab3DSRFe (ORCPT ); Fri, 19 Apr 2013 13:05:34 -0400 Received: from mail-vb0-f49.google.com ([209.85.212.49]:40058 "EHLO mail-vb0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751683Ab3DSRFb (ORCPT ); Fri, 19 Apr 2013 13:05:31 -0400 MIME-Version: 1.0 In-Reply-To: <20130419082546.GA25370@gmail.com> References: <1365811457-31924-1-git-send-email-paul.gortmaker@windriver.com> <20130415093330.GC17715@gmail.com> <1366283681.19383.5.camel@laptop> <51701722.1070407@windriver.com> <20130419082546.GA25370@gmail.com> Date: Fri, 19 Apr 2013 23:05:30 +0600 Message-ID: Subject: Re: [RFC PATCH 0/2] sched: move content out of core files for load average From: Rakib Mullick To: Ingo Molnar Cc: Paul Gortmaker , Peter Zijlstra , Thomas Gleixner , Frederic Weisbecker , LKML Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3586 Lines: 76 On Fri, Apr 19, 2013 at 2:25 PM, Ingo Molnar wrote: > > * Paul Gortmaker wrote: > >> On 13-04-18 07:14 AM, Peter Zijlstra wrote: >> > On Mon, 2013-04-15 at 11:33 +0200, Ingo Molnar wrote: >> >> * Paul Gortmaker wrote: >> >> >> >>> Recent activity has had a focus on moving functionally related blocks of stuff >> >>> out of sched/core.c into stand-alone files. The code relating to load average >> >>> calculations has grown significantly enough recently to warrant placing it in a >> >>> separate file. >> >>> >> >>> Here we do that, and in doing so, we shed ~20k of code from sched/core.c (~10%). >> >>> >> >>> A couple small static functions in the core sched.h header were also localized >> >>> to their singular user in sched/fair.c at the same time, with the goal to also >> >>> reduce the amount of "broadcast" content in that sched.h file. >> >> >> >> Nice! >> >> >> >> Peter, is this (and the naming of the new file) fine with you too? >> > >> > Yes and no.. that is I do like the change, but I don't like the >> > filename. We have _waaaay_ too many different things we call load_avg. >> > >> > That said, I'm having a somewhat hard time coming up with a coherent >> > alternative :/ >> >> Several of the relocated functions start their name with "calc_load..." >> Does "calc_load.c" sound any better? > > Peter has a point about load_avg being somewhat of a misnomer: that's not your > fault in any way, we created overlapping naming within the scheduler and are now > hurting from it. > > Here are the main scheduler 'load' concepts we have right now: > > - The externally visible 'average load' value extracted by tools like 'top' via > /proc/loadavg and handled by fs/proc/loadavg.c. Internally the naming is all > over the map: the fields that are updated are named 'avenrun[]', most other > variables and methods are named calc_load_*(), and a few callbacks are named > *_cpu_load_*(). > > - rq->cpu_load, a weighted, vectored scheduler-internal notion of task load > average with multiple run length averages. Only exposed by debug interfaces but > otherwise relied on by the scheduler for SMP load balancing. > > - se->avg - per entity (per task) load average. This is integrated differently > from the cpu_load - but work is ongoing to possibly integrate it with the > rq->cpu_load metric. This metric is used for CPU internal execution time > allocation and timeslicing, based on nice value priorities and cgroup > weights and constraints. > > Work is ongoing to integrate rq->cpu_load and se->avg - eventually they will > become one metric. > > It might eventually make sense to integrate the 'average load' calculation as well > with all this - as they really have a similar purpose, the avenload[] vector of > averages is conceptually similar to the rq->cpu_load[] vector of averages. > > So I'd suggest to side-step all that existing confusion and simply name the new > file kernel/sched/proc.c - our external /proc scheduler ABI towards userspace. > This is similar to the already existing kernel/irq/proc.c pattern. > Well, kernel/sched/stat.c - also exposes scheduler ABI to userspace. Aren't these things going to introduce confusion (stat.c and proc.c under same sched directory) ? Thanks, Rakib -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/