Messages in this thread | | | Subject | Re: 2.6.8-rc1-np1 | From | Martin Schlemmer <> | Date | Sat, 17 Jul 2004 22:52:32 +0200 |
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On Sat, 2004-07-17 at 11:25, Nick Piggin wrote: > Felipe Alfaro Solana wrote: > > On Sat, 2004-07-17 at 15:23 +1000, Nick Piggin wrote: > > > > > >>Scheduler behaviour is generally pretty good now so I've increased the > >>timeslice size to see how far I can push it. Some workloads really demand > >>small timeslices though, so I've added /proc/sys/kernel/base_timeslice. > >>If you have any problems with the default, please report it to me, and > >>check if lowering this value helps. > > > > > > On my 700Mhz Pentium III Mobile laptop, I feel that 256ms is too high > > for the system to keep interactive when a CPU hog is running. For > > Yeah, it is probably a bit too large here too. A burst of activity > from X can cause xmms to skip slightly. Probably 128 or 64 would > be a decent default. >
Feels fine here on 3GHz P4 (HT system on i875 with dual channel memory, striped raid ST38013AS HDD's). xmms haven't skipped yet (X reniced to -10) and desktop switching is quick. First time typing might be a bit sluggish in gnome-terminal, but second/third char is fine, and vim seems to load fast enough. All this is with a 'make -j24' for kernel (yeah, not really that realistic, but thought I should give it a go) and make -j4 for xorg-x11 going. A few load values is:
load average: 26.72, 15.99, 7.35 load average: 27.93, 19.48, 9.52 load average: 28.02, 19.64, 9.63 load average: 26.01, 19.36, 9.59
base_timeslice is 256 btw ...
> > example, running "while true; do a=2; done" makes the system pretty > > sluggish with the default timeslice. This is noticeable while dragging > > windows around (the movement is jerky and doesn't feel smooth). > > Decreasing the timeslie to 50ms, or even better, 25ms, makes the system > > behave much much better, although it will decrease throughput > > considerably, I guess. > > >
Cannot say I can really feel this test. That with 'make -j4' for X have load:
load average: 2.74, 4.45, 5.98
where the last is still high from the make -j24.
> It usually isn't too bad for desktops, but is more important on > systems with more CPUs and bigger caches. > > On this dual P3 with 256K L2 cache, a make -j8 vmlinux uses > 162.16user 15.43system, ~150ctxsw/s with base_timeslice = 10000 > 163.88user 16.16system, ~300ctxsw/s with base_timeslice = 32 > 192.65user 17.27system, ~1300ctxsw/s with base_timeslice = 1 > > So you come to the point of diminishing returns very quickly, and > 32 or even 16 or 8 are probably fine values for a desktop system > and worth the small cost for CPU intensive tasks. > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- Martin Schlemmer [unhandled content-type:application/pgp-signature] | |