On Sun, Jan 9, 2011 at 1:38 PM, Bakul Shah <bakul+pl...@bitblocks.com> 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
