Date: Sun, 13 Jan 2002 17:48:58 -0800 From: Terry Lambert <tlambert2@mindspring.com> To: Thomas Hurst <tom.hurst@clara.net> Cc: arch@freebsd.org Subject: Re: 64 bit counters again Message-ID: <3C42390A.F9E9F533@mindspring.com> References: <Pine.BSF.4.41.0201132057560.62182-100000@prg.traveller.cz> <3C41F3FD.4ECC8CD@mindspring.com> <20020113231459.GA30349@voi.aagh.net>
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Thomas Hurst wrote: > How about keeping them at 32 bit and also counting the number of times > they've overflowed? User level stuff can then do potentially slow 64 > bit ops if needed. And make it adjacent anyway? Maybe using a union to avoid byte/word order issues? This is much less expensive, I think, since the math doesn't go 64 bit, though it does cost another compare, per over just doing 32 bits. My personal opinion is that the utility of the counters is mostly in the examination of small deltas, or delta measurement over intervals (c.v. the recent "sar" discussion); is there a particular reason that making them more expensive to get 64 bits of accuracy is needed to fulfill? -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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