Re: swap prefetching merge plans

Mike Galbraith
2006-03-26T06:54:03Z

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On Sun, 2006-03-26 at 10:44 +1100, Con Kolivas wrote:
> On Sunday 26 March 2006 02:24, Nick Piggin wrote:
> > Jan Engelhardt wrote:
> > > When will Staircase go in?
> >
> > It is in... the queue ;)
>
> Hah you wish.
>
> No way would I let mainline benefit from something that good. I'm hoarding it
> for -ck only.

Well, my box doesn't think it's _that_ good. I just got done doing some
basic testing, and it is most definitely not ready for primetime. It
has the same problem with sleep as the stock kernel does for instance.

This is bonnie competing with three sleeping cpu hogs.

procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
2 1 3684 13824 4516 818888 0 1 2414 2510 1160 3062 54 5 29 12
1 0 3684 14892 4528 817888 0 0 28 6940 1248 1779 98 2 0 0
1 0 3684 13624 4532 819240 0 0 0 0 1097 1586 99 1 0 0
1 0 3684 14556 4532 818284 0 0 0 0 1181 1709 99 1 0 0
1 0 3684 13688 4532 819184 0 0 0 0 1193 2011 100 0 0 0
1 1 3684 14252 4532 818528 0 0 128 5196 1441 1632 98 2 0 0
1 0 3684 15028 4536 817804 0 0 0 80 1216 1735 99 1 0 0
1 0 3684 13276 4536 819576 0 0 0 0 1157 1650 99 1 0 0
1 0 3684 13976 4540 818832 0 0 4 0 1204 1793 99 1 0 0
1 0 3684 14788 4544 817972 0 0 0 0 1087 1540 100 0 0 0
2 0 3684 13408 4552 819412 0 0 80 6760 1237 1736 98 2 0 0
1 0 3684 14260 4552 818596 0 0 0 4 1091 1564 99 1 0 0
1 0 3684 13144 4556 819712 0 0 0 0 1223 1781 99 1 0 0
1 0 3684 13704 4548 819176 0 0 0 0 1090 1546 99 1 0 0

(after short read, I see it wasn't allowed to compete)

Needless to say, I interrupted it.

It also fails the attached testcase.

-Mike

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#include <stdlib.h>
#include <stdio.h>
#include <signal.h>
#include <unistd.h>

#include <sys/types.h>
#include <sys/wait.h>

volatile unsigned long loop = 10000000;

void
handler (int n)
{
if (loop > 0)
--loop;
}

static int
child (void)
{
pid_t ppid = getppid ();

sleep (1);
while (1)
kill (ppid, SIGUSR1);
return 0;
}

int
main (int argc, char **argv)
{
pid_t child_pid;
int r;

loop = argc > 1 ? strtoul (argv[1], NULL, 10) : 10000000;
printf ("expecting to receive %lu signals\n", loop);

if ((child_pid = fork ()) == 0)
exit (child ());

signal (SIGUSR1, handler);
while (loop)
sleep (1);
r = kill (child_pid, SIGTERM);
waitpid (child_pid, NULL, 0);
return 0;
}