Date: Tue, 24 Apr 2007 15:46:28 +0200 From: des@des.no (Dag-Erling =?iso-8859-1?Q?Sm=F8rgrav?=) To: David G Lawrence <dg@dglawrence.com> Cc: Tim Kientzle <kientzle@freebsd.org>, current@freebsd.org, "Jesper B. Rosenkilde" <jbr@humppa.dk> Subject: Re: Suggestions on Avoiding syscall Overhead Message-ID: <86veflholn.fsf@dwp.des.no> In-Reply-To: <20070424042102.GI38475@tnn.dglawrence.com> (David G. Lawrence's message of "Mon, 23 Apr 2007 21:21:02 -0700") References: <f126fae00704221639l68095de1ye7ce9ba3d921bf20@mail.gmail.com> <20070423113400.GC28587@gw.humppa.dk> <462CD251.9060105@freebsd.org> <20070423161711.GV39474@elvis.mu.org> <462D821F.6030707@freebsd.org> <20070424042102.GI38475@tnn.dglawrence.com>
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David G Lawrence <dg@dglawrence.com> writes: > gettimeofday(2) returns microsecond precision, so I don't see how this > could be made accelerated via a mapped global page. time(3) [which is > currently a wrapper for gettimeofday(2)], on the other had, could be put > into such a page since it only updates once a second. gettimeofday(2) returns a value in microseconds, but this does not necessarily mean that it has microsecond precision. Updating it once per scheduler tick or once per context switch (in userret(), for instance) is probably enough. DES --=20 Dag-Erling Sm=F8rgrav - des@des.no
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