From owner-freebsd-hackers Sat Apr 25 01:56:55 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id BAA28955 for freebsd-hackers-outgoing; Sat, 25 Apr 1998 01:56:55 -0700 (PDT) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from dyson.iquest.net (dyson.iquest.net [198.70.144.127]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id BAA28948 for ; Sat, 25 Apr 1998 01:56:50 -0700 (PDT) (envelope-from toor@dyson.iquest.net) Received: (from root@localhost) by dyson.iquest.net (8.8.8/8.8.8) id DAA07440; Sat, 25 Apr 1998 03:56:39 -0500 (EST) (envelope-from toor) From: "John S. Dyson" Message-Id: <199804250856.DAA07440@dyson.iquest.net> Subject: Re: Context switch time In-Reply-To: from Robert Watson at "Apr 25, 98 04:17:45 am" To: robert@cyrus.watson.org Date: Sat, 25 Apr 1998 03:56:39 -0500 (EST) Cc: freebsd-hackers@FreeBSD.ORG X-Mailer: ELM [version 2.4ME+ PL38 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > > Hi, > > I was wondering what the average context switch time across a syscall > invocation is, also, how long it takes to switch in a different process. > Presumably just on a Pentium 100ish processor. Is this data I can > retrieve from the kernel profiler? mi_switch and tsleep both appear in > the profiling data, but it is not clear to me that this includes the time > for the switch to kernel context, etc. > > Thanks, > > Robert N Watson > For a first start, try lat_ctx from lmbench. I believe that it does a token passing scheme with pipes, so it won't tell you exactly what you want, but might be ballpark. John To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message