Date: Sat, 29 May 2004 21:08:21 -0400 (EDT) From: Robert Watson <rwatson@freebsd.org> To: "Marc G. Fournier" <scrappy@hub.org> Cc: freebsd-current@freebsd.org Subject: Re: SCHED_BSD vs SCHED_ULE ... Message-ID: <Pine.NEB.3.96L.1040529210431.74482a-100000@fledge.watson.org> In-Reply-To: <20040529203815.G907@ganymede.hub.org>
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On Sat, 29 May 2004, Marc G. Fournier wrote: > Is there a circumstance where the older SCHED is better then ULE? Yes. I've noticed differing performance properties based on a number of factors, including hardware variation and workload. I've also noticed a couple of bugs in ULE that I'm hoping Jeff Roberson gets a chance to fix at some point, including some issues with load balancing. > Or is the older one something that will eventually just be removed > altogether? > > If the older does have areas in which it is the better, are there any > docs comparing the two? Well, I think it's useful to keep around 4BSD even if only to use as a performance baseline for understanding where ULE is working better or worse. I don't know of any specific documents talking about relative merits: generally, I would consider if a bug if ULE is consistently slower in some form. As such, any document would probably be an excellent bug report :-). As people run into performance issues with -CURRENT, the scheduler is one of the first variables I would ask someone to check, FYI. And in that sense, keeping 4BSD around is extremely valuable. Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert@fledge.watson.org Senior Research Scientist, McAfee Research
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