From owner-freebsd-current@FreeBSD.ORG Fri Nov 19 00:17:10 2010 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: by hub.freebsd.org (Postfix, from userid 1233) id 169521065694; Fri, 19 Nov 2010 00:17:10 +0000 (UTC) Date: Fri, 19 Nov 2010 00:17:10 +0000 From: Alexander Best To: Julian Elischer Message-ID: <20101119001710.GA14641@freebsd.org> References: <4CE50849.106@zedat.fu-berlin.de> <4CE52177.3020306@freebsd.org> <20101118182324.GA36312@freebsd.org> <20101118182852.GR63683@over-yonder.net> <20101118185635.GA43706@freebsd.org> <20101118170623.7f9c14f3@kan.dnsalias.net> <20101118233731.GA10392@freebsd.org> <4CE5BA37.20604@freebsd.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4CE5BA37.20604@freebsd.org> Cc: FreeBSD@freebsd.org, FreeBSD Stable , "O. Hartmann" , "Matthew D. Fuller" , Current , Andriy Gapon , freebsd-performance@freebsd.org, Daniel Nebdal Subject: Re: TTY task group scheduling X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 19 Nov 2010 00:17:10 -0000 On Thu Nov 18 10, Julian Elischer wrote: > On 11/18/10 3:37 PM, Alexander Best wrote: > >On Fri Nov 19 10, Daniel Nebdal wrote: > >>On Fri, Nov 19, 2010 at 12:06 AM, Alexander Kabaev > >>wrote: > >>>On Thu, 18 Nov 2010 18:56:35 +0000 > >>>Alexander Best wrote: > >>> > >>>>On Thu Nov 18 10, Matthew D. Fuller wrote: > >>>>>On Thu, Nov 18, 2010 at 06:23:24PM +0000 I heard the voice of > >>>>>Alexander Best, and lo! it spake thus: > >>>>>>judging from the videos the changes are having a huge impact imo. > >>>>>Well, my (admittedly limited, and certainly anecdotal) experience is > >>>>>that Linux's interactive response when under heavy load was always > >>>>>much worse than FreeBSD's. So maybe that's just them catching up to > >>>>>where we already are ;) > >>>>well...i tried playing back a 1080p vide files while doing > >>>>`make -j64 buildkernel` and FreeBSD's interactivity seems far from > >>>>perfect. > >>>One thing that just begs to be asked: since when decoding 1080p became > >>>an interactive task? > >>> > >>Strictly speaking it isn't - but displaying it is a timing-sensitive > >>task that isn't CPU- or I/O-bound, and scheduling-wise that probably > >>makes it more like the "fast response when woken up" interactive tasks > >>than a CPU-bound non-interactive process. > >>Decoding it into another file on the disk is in the latter category, > >>of course - but I don't think that's what he meant. :) > >> > >>More on topic - while this was a tiny patch for Linux, it seems like > >>it would take more work for us, since I don't believe either of the > >>schedulers handles task groups in the required way. The linux patch > >>was just "create task groups automatically", since they already had > >>some suitable logic for scheduling based on task groups in their CFS > >>scheduler. We would have to (re-)add that first, which is non-trivial. > >personally i think freebsd would hugely benefit from a scheduler framework > >such as geom/gsched, where it's easy to switch between various algorithms. > > > >that way it be much easier to try out new concepts without having to write > >a > >completely new scheduler. > > we are part of the way there.. > > at least we did abstract the scheduler to the point where > we have two completely different ones. > you are welcome to develop a 'framework as you describe and plug it into > the abstraction we already have. **** 17:49 @ arundel : also looking at the svn log shows that still a lot of \ commits happen to sched_4bsd. so it's defenately not being abbandoned. in \ fact there might be situations where it performs better than sched_ule. 17:50 @ arundel : i'm looking forward to a scheduler which looks sorta like \ geom and enables you to plugin addition plugins with different scheduling \ algorithms. :) 17:51 @ Genesys : Luigi Rizzo had a plugabble scheduler back in 4.* or \ thereabouts 17:51 @ Genesys : you could kldload new ones and switch to them on the fly 17:52 @ arundel : wow. that sounds cool. too bad it didn't make it into src \ tree. by now it's probably outdated and needs to be reworked quite a bit. **** does anybody know something about this? i'm sorry. i'd really love to contribute some code, but my programing skills are pretty scrappy. ;) it would probably take me 20 years to figure out the current sched code. cheers. alex > > >cheers. > >alex > > > >> > >>-- > >>Daniel Nebdal -- a13x