Date: Thu, 15 Dec 2011 09:44:23 +0000 From: Tom Evans <tevans.uk@googlemail.com> To: Jeremy Chadwick <freebsd@jdc.parodius.com> Cc: freebsd-stable@freebsd.org Subject: Re: SCHED_ULE should not be the default Message-ID: <CAFHbX1KdsvKBPvpxQG-dL1szxk4FB86WxQF-Cw1PWLf=7pQg7w@mail.gmail.com> In-Reply-To: <20111215004205.GA11556@icarus.home.lan> References: <4EE1EAFE.3070408@m5p.com> <CAJ-FndDniGH8QoT=kUxOQ%2BzdVhWF0Z0NKLU0PGS-Gt=BK6noWw@mail.gmail.com> <4EE2AE64.9060802@m5p.com> <4EE88343.2050302@m5p.com> <CAFHbX1%2B5PttyZuNnYot8emTn_AWkABdJCvnpo5rcRxVXj0ypJA@mail.gmail.com> <4EE933C6.4020209@zedat.fu-berlin.de> <20111215004205.GA11556@icarus.home.lan>
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On Thu, Dec 15, 2011 at 12:42 AM, Jeremy Chadwick <freebsd@jdc.parodius.com> wrote: > On Thu, Dec 15, 2011 at 12:39:50AM +0100, O. Hartmann wrote: >> On 12/14/11 18:54, Tom Evans wrote: >> > I believe the correct thing to do is to put some extra documentation >> > into the handbook about scheduler choice, noting the potential issues >> > with loading NCPU+1 CPU bound processes. Perhaps making it easier to >> > switch scheduler would also help? > > Replying to Tom's comment here: > > It is already easy to switch schedulers. =C2=A0You change the option in y= our > kernel config, rebuild kernel (world isn't necessary as long as you > haven't csup'd between your last rebuild and now), make installkernel, > shutdown -r now, done. Your definition of 'easy' differs wildly from mine. How is that in any way 'easy' to do across 200 servers? > > If what you're proposing is to make the scheduler changeable in > real-time? =C2=A0I think that would require a **lot** of work for somethi= ng > that very few people would benefit from (please stop for a moment and > think about the majority of the userbase, not just niche environments; I > say this politely, not with any condescension BTW). =C2=A0Sure, it'd be > "nice to have", but should be extremely low on the priority list (IMO). Real time scheduler changing would be insane! I was thinking that both/any/all schedulers could be compiled into the kernel, and the choice of which one to use becomes a boot time configuration. You don't have to recompile the kernel to change timecounter. Cheers Tom
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