Date: Tue, 16 Oct 2001 10:34:18 -0700 (PDT) From: John Baldwin <jhb@FreeBSD.org> To: Luigi Rizzo <rizzo@aciri.org> Cc: arch@FreeBSD.org Subject: Re: where to put support for timestamping kernel events ? Message-ID: <XFMail.011016103418.jhb@FreeBSD.org> In-Reply-To: <20011016100520.E63982@iguana.aciri.org>
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On 16-Oct-01 Luigi Rizzo wrote: > On Tue, Oct 16, 2001 at 09:27:07AM -0700, John Baldwin wrote: >> >> On 15-Oct-01 Luigi Rizzo wrote: >> > [Apparently this kind of question is better asked on -arch, >> > so sorry for the repost, here it goes again... and in the meantime >> > i have had some time to elaborate on names and locations.] >> >> Note that KTR has somewhat similar support for this, though it currently > > what is KTR ? any pointers ? (sorry but i am not familiar > with -current, where this seems to be...) KTR is an kernel event trace mechanism. current includes both ktr(4) and ktr(9) manpages. It basically allows you to log events in a printf-style fashion in the kernel including a timestamp among other things. >> doesn't use the TSC. It could be changed to use cpu_cyclecount() (which is >> a >> MI interface which uses the TSC when it can) perhaps which might help. >> Unfortunately, the KTR buffr isn't exported via sysctl(8) at the moment. > > well, the sysctl export is really trivial to do. Except on an SMP system when aother CPU may be sticking items in the buffer while you are exporting it. > cheers > luigi -- John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/ PGP Key: http://www.baldwin.cx/~john/pgpkey.asc "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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