Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755501Ab0LDRjv (ORCPT ); Sat, 4 Dec 2010 12:39:51 -0500 Received: from mail-ww0-f44.google.com ([74.125.82.44]:43155 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754657Ab0LDRjt convert rfc822-to-8bit (ORCPT ); Sat, 4 Dec 2010 12:39:49 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=wzNHmgj4hu3/d1KW011WffV59YmD6mKgKPEduMGVjLmbnFeR8CYAu7NOpd/PNb0+UE DhPTfFUfbG233EN29pQ5vNr6NFu9M/9gofuZj+QVxHQG5wLB+0cFKjf3rLEzXdDfJIUP SQKAatNjrLOTzHPDkOQ06WCdaPaVdzdorh2cU= MIME-Version: 1.0 In-Reply-To: <1290281700.28711.9.camel@maggy.simson.net> References: <1289783580.495.58.camel@maggy.simson.net> <1289811438.2109.474.camel@laptop> <1289820766.16406.45.camel@maggy.simson.net> <1289821590.16406.47.camel@maggy.simson.net> <20101115125716.GA22422@redhat.com> <1289856350.14719.135.camel@maggy.simson.net> <20101116130413.GA29368@redhat.com> <1289917109.5169.131.camel@maggy.simson.net> <20101116150319.GA3475@redhat.com> <1289922108.5169.185.camel@maggy.simson.net> <20101116172804.GA9930@elte.hu> <1290281700.28711.9.camel@maggy.simson.net> Date: Sat, 4 Dec 2010 12:39:48 -0500 X-Google-Sender-Auth: 0STZxN6wsFulkcHK0CZ96l0Y9kM Message-ID: Subject: Re: [PATCH v4] sched: automated per session task groups From: Colin Walters To: Mike Galbraith Cc: Ingo Molnar , Oleg Nesterov , Peter Zijlstra , Linus Torvalds , Markus Trippelsdorf , Mathieu Desnoyers , LKML Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1805 Lines: 37 On Sat, Nov 20, 2010 at 2:35 PM, Mike Galbraith wrote: > A recurring complaint from CFS users is that parallel kbuild has a negative > impact on desktop interactivity.  This patch implements an idea from Linus, > to automatically create task groups.  This patch only per session autogroups, > but leaves the way open for enhancement. Resurrecting this thread a bit, one question I didn't see discussed is simply: Why doesn't "nice" work for this? On my Fedora 14 system, "ps alxf" shows almost everything in my session is running at the default nice 0. The only exceptions are "/usr/libexec/tracker-miner-fs" at 19, and pulseaudio at -11. I don't know What would happen if say the scheduler effectively group-scheduled each nice value? Then, what we tell people to do is run "nice make". Which in fact, has been documented as a thing to do for decades. Actually I tend to use "ionice" too, which is also useful if any of your desktop applications happen to make the mistake of doing I/O in the mainloop (emacs fsync()ing in UI thread, I'm looking at you). Quickly testing kernel-2.6.35.6-48.fc14.x86_64 on a "Intel(R) Core(TM)2 Quad CPU Q9400 @ 2.66GHz", the difference between "make -j 128" and "nice make -j 128" is quite noticeable. As you'd expect. The CFS docs already say: "The CFS scheduler has a much stronger handling of nice levels and SCHED_BATCH than the previous vanilla scheduler: both types of workloads are isolated much more aggressively" Does it just need to be even more aggressive, and people use "nice"? -- 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/