Date: Sat, 20 Mar 1999 19:19:26 +0100 (MET) From: Luigi Rizzo <luigi@labinfo.iet.unipi.it> To: bf20761@binghamton.edu (zhihuizhang) Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Calculation of load average and CCPU_SHIFT Message-ID: <199903201819.TAA02543@labinfo.iet.unipi.it> In-Reply-To: <Pine.SOL.L3.93.990320150853.18347B-100000@bingsun1> from "zhihuizhang" at Mar 20, 99 03:17:56 pm
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> I am looking into the source code in file vm_meter.c and kern_synch.c of > FreeBSD 2.2.8. They use integer multiplication and shift operation to > replace the costly float multiplication. The FSCALE and FSHIFT are for it is not only costly (actually, on modern CPUs it is not costly at all!), FPU usage is not allowed in the kernel. cheers luigi To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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