From owner-freebsd-hackers@FreeBSD.ORG Tue Apr 10 20:50:40 2012 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id A40D51065672 for ; Tue, 10 Apr 2012 20:50:40 +0000 (UTC) (envelope-from lacombar@gmail.com) Received: from mail-we0-f182.google.com (mail-we0-f182.google.com [74.125.82.182]) by mx1.freebsd.org (Postfix) with ESMTP id 29A118FC0A for ; Tue, 10 Apr 2012 20:50:40 +0000 (UTC) Received: by wern13 with SMTP id n13so182103wer.13 for ; Tue, 10 Apr 2012 13:50:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=3Mx9yRLC5GYdE1EmQw4gUfpEQB14yRqBQ7oHyzJh7l4=; b=JDEsjtZM2fvUIczDxNIHNjAXtJ7iVWtkfdZBr1iedCo4cO/FapeU/GaGHMFwhvX/vc 2ROQkEDZfTnzVPeHDPl/JlgzQHpJRZUjFx4RVvSkoGm+opVkw+FanVgBTPo6OzKyqJL5 UA1wmWpLnqfLb4pePL/v+1SXjyCITgz1FKz+Kf7rv/br6eAR424c9/g6mwBmlHUGCHTw Ys27u8Z97NzBBOqpb8jNHb6cmtix10MQNQTngTeZpRCLSKuxEjIqOrgmww0wfBleWozT NjEd//e2pIlJNt5/9UN1bdR7XAYpZH5E1EECMq18pduCwebGv6/ii6H5aciR9KSi/0PE ifNg== MIME-Version: 1.0 Received: by 10.180.79.135 with SMTP id j7mr523658wix.19.1334091039244; Tue, 10 Apr 2012 13:50:39 -0700 (PDT) Received: by 10.216.49.81 with HTTP; Tue, 10 Apr 2012 13:50:39 -0700 (PDT) In-Reply-To: <20120410160513.0b322f68@bhuda.mired.org> References: <4F2F7B7F.40508@FreeBSD.org> <4F366E8F.9060207@FreeBSD.org> <4F367965.6000602@FreeBSD.org> <4F396B24.5090602@FreeBSD.org> <4F3978BC.6090608@FreeBSD.org> <4F3990EA.1080002@FreeBSD.org> <4F3C0BB9.6050101@FreeBSD.org> <4F3E807A.60103@FreeBSD.org> <4F3E8858.4000001@FreeBSD.org> <4F7DE863.6080607@FreeBSD.org> <4F833F3D.7070106@FreeBSD.org> <20120410160513.0b322f68@bhuda.mired.org> Date: Tue, 10 Apr 2012 16:50:39 -0400 Message-ID: From: Arnaud Lacombe To: Mike Meyer Content-Type: text/plain; charset=ISO-8859-1 Cc: freebsd-hackers@freebsd.org Subject: Re: [RFT][patch] Scheduling for HTT and not only X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 10 Apr 2012 20:50:40 -0000 Hi, On Tue, Apr 10, 2012 at 4:05 PM, Mike Meyer wrote: > On Tue, 10 Apr 2012 12:58:00 -0400 > Arnaud Lacombe wrote: >> Let me disagree on your conclusion. If OS A does a task in X seconds, >> and OS B does the same task in Y seconds, if Y > X, then OS B is just >> not performing good enough. > > Others have pointed out one problem with this statement. Let me point > out another: > > It ignores the purpose of the system. If you change the task to doing > N concurrent versions of the task, and OS A time increases linearly > with the number of tasks (say it's time X*N) but OS B stair-steps at > the number of processors in the system (i.e. Y*floor(N/P)), then OS A > is just not performing good enough. > > A more concrete example: if OS B spends a couple of microseconds > optimizing disk access order and OS A doesn't, then a single process > writing to disk on OS A could well run faster than the same on OS > B. However, the maximum throughput on OS B as you add process will be > higher than it is on OS A. Which one you want will depend on what > you're using the system for. > You are discussing implementations in both case. If the implementation is not good enough, let's improve it, but do not discard the numbers on false claims. - Arnaud