Date: Sat, 08 Aug 1998 23:49:51 -0700 From: David Greenman <dg@root.com> To: Greg Lehey <grog@lemis.com> Cc: John Baldwin <jobaldwi@vt.edu>, FreeBSD Hackers <hackers@FreeBSD.ORG> Subject: Re: AMD-specific kernel code (was: How long a wait?) Message-ID: <199808090649.XAA23702@implode.root.com> In-Reply-To: Your message of "Sun, 09 Aug 1998 16:08:29 %2B0930." <19980809160829.A11214@freebie.lemis.com>
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>The effect on CPU performance is also noticable: here are "make >world" times: > >Without write allocate: > >real 106m58.441s >user 63m0.960s >sys 20m25.035s > >With write allocate: > >real 114m16.402s >user 69m41.733s >sys 17m54.862s > >These were only a rough test (I had other stuff running at the same >time), but in practice this normally only makes about 1 minute >difference. I'd guess that the difference *is* real. Obviously there >must be a reason for enabling or disabling this behaviour, and I'd >guess that write allocation is most effective when one process is >using much CPU time. 'make world' starts thousands of short-lived >process, and may thus be the worst-case scenario. In this connection, >it's also interesting to note that system time was down and user time >was up with write allocation. > >I have patches available. Does anybody want to commit them? Based on the above performance numbers, I'd say no - they appear to be a pessimization. -DG David Greenman Co-founder/Principal Architect, The FreeBSD Project To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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