On Wed, 18 Apr 2001, Laurent Chavet wrote:
> Try this (my example I've 2GB of ram)
>
> turn all your swap off
>
> dd about 15% of the size of your RAM:
> dd if=/dev/zero of=/local/test count=300 bs=1000000
>
> Run this program with SIZE about 95% of your RAM:
>
> #include <stdlib.h>
> #include <unistd.h>
> #include <assert.h>
>
> #define SIZE (1900 * 1024 * 1024)
> int main()
> {
> int i;
> char *p = malloc(SIZE);
> assert (p != NULL);
> for (i = 0; i < SIZE; i++)
> p[i] = 1;
> printf ("done %p\n", p);
>
> while (1)
> {
> sleep (60);
> }
> return 0;
> }
>
>
> Watch top: when this program needs the memory that kswapd keep
> in cache they go both at 100% cpu (on SMP) but still the size of
> the program only grows at about 100KB/s, why is kswapd releasing
> it so slowly and taking so much CPU ?
Because kswapd still has to scan all the (unfreeable) memory
of the big process to determine it isn't freeable.
At the moment kswapd is really stupid about these corner-case
situations, please bear with us while we fix it ...
... and don't forget to fill in a bugzilla item on the
Linux-MM bugzilla ;)
regards,
Rik
--
Linux MM bugzilla: http://linux-mm.org/bugzilla.shtml
Virtual memory is like a game you can't win;
However, without VM there's truly nothing to lose...
http://www.surriel.com/
http://www.conectiva.com/ http://distro.conectiva.com/
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