Date: Tue, 28 Feb 2006 16:15:15 +0000 From: David Malone <dwmalone@maths.tcd.ie> To: Vlad GALU <vladgalu@gmail.com> Cc: freebsd hackers <freebsd-hackers@freebsd.org> Subject: Re: Fastest timecounter ? Message-ID: <20060228161515.GA44849@jbell.maths.tcd.ie> In-Reply-To: <79722fad0602270809p2229db83i5cb4cf0b24f91828@mail.gmail.com> References: <79722fad0602270809p2229db83i5cb4cf0b24f91828@mail.gmail.com>
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On Mon, Feb 27, 2006 at 06:09:26PM +0200, Vlad GALU wrote: > I wrote a piece of software that has to get the current > timestamp, one way or the other, a huge number of times per second. > Apart from the empyrical tests one can perform to find out the > timekeeping scheme with the less performance impact, is there any rule > of thumb as to what choice to go for ? The TSC is always fastest, but unfortunately under some circumstances it can't be trusted (if your CPU has throttle modes to save power or on some SMP systems where the two TSCs in each CPU give different values). David.
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