Date: Thu, 18 Nov 2010 23:37:31 +0000 From: Alexander Best <arundel@freebsd.org> To: Daniel Nebdal <dnebdal@gmail.com> Cc: FreeBSD@freebsd.org, FreeBSD Stable <freebsd-stable@freebsd.org>, Andriy Gapon <avg@freebsd.org>, Current <freebsd-current@freebsd.org>, "Matthew D. Fuller" <fullermd@over-yonder.net>, freebsd-performance@freebsd.org, "O. Hartmann" <ohartman@zedat.fu-berlin.de> Subject: Re: TTY task group scheduling Message-ID: <20101118233731.GA10392@freebsd.org> In-Reply-To: <AANLkTik6pnd-JCjkGZv3Dr7SjfwAgyqM=J8FPotM2-BD@mail.gmail.com> References: <AANLkTinHSX1%2Bs3hrHyDeU2Vfp6zekTe04XkHhTc2jtLv@mail.gmail.com> <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> <AANLkTik6pnd-JCjkGZv3Dr7SjfwAgyqM=J8FPotM2-BD@mail.gmail.com>
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On Fri Nov 19 10, Daniel Nebdal wrote: > On Fri, Nov 19, 2010 at 12:06 AM, Alexander Kabaev <kabaev@gmail.com> wrote: > > On Thu, 18 Nov 2010 18:56:35 +0000 > > Alexander Best <arundel@freebsd.org> 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. cheers. alex > > > -- > Daniel Nebdal -- a13x
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