From mboxrd@z Thu Jan 1 00:00:00 1970 MIME-Version: 1.0 In-Reply-To: <20110109213849.939D75B42@mail.bitblocks.com> References: <16094d5a594bfa72dd0e9ac6f3f8b31c@plug.quanstro.net> <20110109195426.D1ED35B42@mail.bitblocks.com> <20110109213849.939D75B42@mail.bitblocks.com> Date: Sun, 9 Jan 2011 13:56:00 -0800 Message-ID: From: ron minnich To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net> Content-Type: text/plain; charset=ISO-8859-1 Subject: Re: [9fans] fs performance Topicbox-Message-UUID: 93139404-ead6-11e9-9d60-3106f5b1d025 On Sun, Jan 9, 2011 at 1:38 PM, Bakul Shah wrote: > I didn't say plan9 "suffers". Merely that one has to look at > other aspects as well (implying putting in Tstream may not > make a huge difference). well, what we do know from one set of measurements is that it makes a measurable difference when latency is measured in the tens of milliseconds. :-) I have done some of these other measurements, e.g. system call overhead. Plan 9 system call time is quite a bit longer than Linux nowadays, when Linux uses the SYSENTER support. At the same time, the Plan 9 "mon" device that Andrey wrote was considerably faster than the procfs-based "mon" device I wrote: 30K samples/second on Plan 9 vs. 12K samples/second on Linux. John did do some measurement of file system times via the trace device we wrote. I think it's fair to say that the IO path for fossil is considerably slower than the IO path for kernel-based file systems in Linux: slower as in multiples of 10, not multiples. There's a fair amount of copying, allocation, and bouncing in and out of the kernel, and this activity does not come cheap. So, one speculation is that a kernel-based Plan 9 file system might be quite fast. And that's enough random text for a Sunday. ron