Date: Thu, 12 Jun 2014 14:59:48 +0200 From: Eivind Evensen <eivinde@terraplane.org> To: George Mitchell <george+freebsd@m5p.com> Cc: freebsd-stable@freebsd.org Subject: Re: Not to beat a dead horse, but ... Message-ID: <20140612125948.GB22660@klump.hjerdalen.lokalnett> In-Reply-To: <5394A848.7030609@m5p.com> References: <5394A848.7030609@m5p.com>
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On Sun, Jun 08, 2014 at 02:15:36PM -0400, George Mitchell wrote: > Since the majority of my systems are uniprocessors and I like to > run dnetc, SCHED_ULE has been a dealbreaker for me since day one. > Consequently I can't use freebsd_update. > > The party line seems to be, "Well, everybody knows SCHED_ULE sucks > on uniprocessors." Hello? Not everybody has upgraded to multiple > core or hyperthreaded processors yet. Do we really want to write > off every uniprocessor piece of hardware out here? > > The other assertion I hear is that SCHED_ULE really excels on some > unspecified workload or other. I'd love to see exactly how much > better it does than 4BSD on these mythological loads. -- George It doesn't seem to be only for uniprocessor systems 4BSD is the better choice. Another time when the schedulers were discussed on these lists, I checked first the ULE one which I was using, then 4BSD with a workload I knew rendered the two core machine close to unusable. I simply disconnected power to get some unclean filesystems and then tried to use the machine while the background filesystem check was running. Usage was running texteditors, X, ssh, browsers and the like. 4BSD performed better. The machine was almost usable with a little patience. Since then I've usually changed to 4BSD on other machines aswell, and at least on one 4 core machine, I notice that according to top, load is spread more even among the processors. While compiling base and some ports at the same time I've seen ULE keeping one processor busy while the others are close to 100 % idle, while 4BSD seems to keep all atleast halfway busy. I don't have any numbers other than that though, changing to 4BSD comes more from how I've the experienced using the system with each of them feels like. Eivind N Evensen
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