Messages in this thread | | | Date | Mon, 24 Nov 2003 08:37:29 +0100 | From | "Ihar 'Philips' Filipau" <> | Subject | Re: Do I need kswapd if I don't have swap? |
| |
Can you try 2.6?
AFAIK 2.4 has no callpath to return ENOMEM to user space. (probably in couple of months I will reach this issue on my systems and test it completely).
kswapd is universal process to write-out information to disk - and in Linux pages has no any difference as kswapd concerned. It just dumbly write them out. If you will disable kswapd - files modified by mean of mmap() most likely will never be written back to disk. (Here I am (most likely) wrong - probably some of the vm gurus can correct me). That's actually why Linux has problems with disk cache and disk cache can easily swap the task doing i/o.
If you want to work-around this situation - enable OOM. it will just kill your process instead.
David Wuertele wrote: > Using 2.4.18 on my 32MB RAM embedded MIPS system, malloc() goes > bye-bye: > > /* Malloc as much as possible, then return */ > #include <stdio.h> > #define UNIT 1024 /* one kilobyte */ > int main () > { > unsigned int j, totalmalloc=0, totalwrote=0, totalread=0; > while (1) { > unsigned char *buf = (unsigned char *) malloc (UNIT); > if (!buf) return 0; > totalmalloc += UNIT; fprintf (stderr, "%u ", totalmalloc); > for (j=0; j<UNIT; j++) buf[j] = j % 256; > totalwrote += UNIT; fprintf (stderr, "%u ", totalwrote); > for (j=0; j<UNIT; j++) if (buf[j] != (j % 256)) return -1; > totalread += UNIT; fprintf (stderr, "%u\n", totalread); > } > } > > I expected this program to malloc most of my embedded MIPS's 32MB of > system RAM, then eventually return with a -1 or a -2. Unfortunately, > it hangs having finally printed: > > M26916864 > W26916864 > R26916864 > > The malloc call isn't even returning. What could explain that? > > I don't have swap space configured, and I notice several kernel > threads that I figure might be assuming I have swap. For example: > > 3 root S [ksoftirqd_CPU0] > 4 root S [kswapd] > 5 root S [bdflush] > 6 root S [kupdated] > 7 root S [mtdblockd] > > Do I need any of these if I don't have swap? Are there any special > kernel configs I should be doing if I don't have swap? >
- 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/
| |