Nick Piggin wrote:
> Forward port of nicksched to 2.6.21-rc4.
Great!
> Can't find my old
> design/description document for it, but it is yet another scheduler. Focus
> is on simplicity and fairness.
Simplicity is really key.
> This one tends to require X to be reniced to -10 or so for best results
> (renice -10 `pidof X`).
No problem.
> Timeslices get scaled by /proc/sys/kernel/base_timeslice. If you have bad
> interactivity you could try lowering this and see if it helps.
As I am on 2.6.20, I can't really test this patch, but I tried your sched
from PlugSched and its not bad.
I'm getting strange numbers with chew.c, though. Try this:
Boot into /bin/sh
Run ./chew on one console.
Run ./chew on another console.
Watch latencies.
Console 1:
pid 671, prio 0, out for 799 ms, ran for 800 ms, load 50%
pid 671, prio 0, out for 799 ms, ran for 801 ms, load 50%
pid 671, prio 0, out for 799 ms, ran for 799 ms, load 49%
pid 671, prio 0, out for 800 ms, ran for 800 ms, load 49%
Console 2:
pid 672, prio 0, out for 800 ms, ran for 799 ms, load 49%
pid 672, prio 0, out for 799 ms, ran for 800 ms, load 50%
pid 672, prio 0, out for 799 ms, ran for 800 ms, load 50%
pid 672, prio 0, out for 799 ms, ran for 799 ms, load 49%
pid 672, prio 0, out for 799 ms, ran for 799 ms, load 49%
Looks good, but now add a cpu-hog, ie. while :; do :; done
Console 1:
pid 671, prio 0, out for 799 ms, ran for 399 ms, load 33%
pid 671, prio 0, out for 799 ms, ran for 399 ms, load 33%
pid 671, prio 0, out for 799 ms, ran for 399 ms, load 33%
pid 671, prio 0, out for 799 ms, ran for 399 ms, load 33%
Console 2:
pid 672, prio 0, out for 1599 ms, ran for 799 ms, load 33%
pid 672, prio 0, out for 1599 ms, ran for 799 ms, load 33%
pid 672, prio 0, out for 1599 ms, ran for 800 ms, load 33%
pid 672, prio 0, out for 1599 ms, ran for 799 ms, load 33%
It's smooth, but latencies are double on console2. Easy enough to fix,
though, just press scrollock to induce a sleep and then release.
Also, latencies are huge. Is there a way to fix latencies per nice?
Thanks!
--
Al
/*
* original idea by Chris Friesen. Thanks.
*/
#include <stdio.h>
#include <sys/time.h>
#include <sys/resource.h>
#define THRESHOLD_USEC 2000
unsigned long long stamp()
{
struct timeval tv;
gettimeofday(&tv, 0);
return (unsigned long long) tv.tv_usec + ((unsigned long long) tv.tv_sec)*1000000;
}
int main()
{
unsigned long long thresh_ticks = THRESHOLD_USEC;
unsigned long long cur, last, start, act;
struct timespec ts;
sched_rr_get_interval(0, &ts);
printf("pid %d, prio %3d, interval of %d nsec\n", getpid(), getpriority(PRIO_PROCESS, 0), ts.tv_nsec);
start = last = stamp();
while(1) {
cur = stamp();
unsigned long long delta = cur-last;
if (delta > thresh_ticks) {
act = last - start;
printf("pid %d, prio %3d, out for %4llu ms, ran for %4llu ms, load %3llu%\n"
, getpid(), getpriority(PRIO_PROCESS, 0), delta/1000, act/1000,(act*100)/(cur-start));
start = cur = stamp();
}
last = cur;
}
return 0;
}
