Date: Wed, 19 Jul 2000 23:41:24 -0500 From: Alan Cox <alc@cs.rice.edu> To: Lars Eggert <larse@isi.edu> Cc: hackers@freebsd.org Subject: Re: clearing pages in the idle loop Message-ID: <20000719234124.H14543@cs.rice.edu>
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Last year, I tried to reproduce some of the claims/results in this paper on FreeBSD/x86 and couldn't. I also tried limiting the idle loop to clearing pages of one particular color at a time. That way, the cache lines replaced by the second page you clear are the cache lines holding the first page you cleared, and so on for the third, fourth, ... pages cleared. Again, I saw no measurable effect on tests like "buildworld", which is a similar workload to the paper's if I recall correctly. Finally, it's possible that having these pre-zeroed pages in your L2 cache might be beneficial if they get allocated and used right away. FreeBSD's idle loop zeroes the pages that are next in line for allocation. Alan To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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