Date: Fri, 17 Nov 2000 17:05:41 +0900 From: Kenjiro Cho <kjc@csl.sony.co.jp> To: mark@grondar.za Cc: arch@freebsd.org Subject: Re: new monotime() call for all architectures. Message-ID: <20001117170541F.kjc@csl.sony.co.jp> In-Reply-To: <200011170655.eAH6tCJ05746@gratis.grondar.za> References: <200011170655.eAH6tCJ05746@gratis.grondar.za>
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Mark Murray wrote: > I need a fast-as-possible "time" inside the kernel to help > speed up the /dev/random device. I say "time", because although > it needs to be a function of time (preferably accurate and linear), > it has no need whatsoever to be "real time", so a simple counter > is quite OK. > > Pentiums, Alphas and IA64's all have a suitable register on chip, > while I have to make do with nanotime(9) on i386 and i486. > > I have prepared a monotime(9) call for the i386, alpha and ia64 > architectures (patch enclosed). I have been running this for a > week or two now with promising results (on a Pentium). With > the exception of the minimum of "glue" (and nanotime on older > architectures), these functions reduce to one instruction. > > Comments? Suggestions? Nobel Prize nominations? I'd like to > commit this soonish if possible. The PCC (Processor Cycle Counter) register on alpha is 64 bits but only the lower 32 bits is a counter. -Kenjiro To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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