Date: Mon, 1 Oct 2007 17:37:10 +1000 (EST) From: Bruce Evans <brde@optusnet.com.au> To: Jeff Roberson <jroberson@chesapeake.net> Cc: src-committers@freebsd.org, Kevin Oberman <oberman@es.net>, cvs-src@freebsd.org, Jeff Roberson <jeff@freebsd.org>, Garance A Drosehn <gad@freebsd.org>, Ben Kaduk <minimarmot@gmail.com>, cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/kern sched_ule.c Message-ID: <20071001172620.X1839@besplex.bde.org> In-Reply-To: <20070930153430.U583@10.0.0.1> References: <20070930040318.094E345018@ptavv.es.net> <20070930153430.U583@10.0.0.1>
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On Sun, 30 Sep 2007, Jeff Roberson wrote: > On Sat, 29 Sep 2007, Kevin Oberman wrote: >> YMMV, but ULE seems to generally work better then 4BSD for interactive >> uniprocessor systems. The preferred scheduler for uniprocessor servers >> is less clear, but many test have shown ULE does better for those >> systems in the majority of cases. > > I feel it's safe to say desktop behavior on UP is definitely superior. This is unsafe to say. > I > think there is no significant difference on UP between 4BSD and ULE This may be safe to say, but is inconsistent with the above. > except > perhaps in context switching microbenchmarks where ULE falls behind. It is safe to say that interactive users cannot notice insignificant differences. It takes a micro-benchmark to notice possibly-significant differences of hundreds or even thousands of nanonseconds for context switching. ULE may give higher priority to interactive processes, but most loss of interactivity is caused by blocking on I/O, and there is nothing nothing a scheduler can do to speed up slow or overloaded devices. Bruce
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