Re: Good way to free as much memory as possible under 2.5.34?

From: Pavel Machek (pavel@ucw.cz)
Date: Fri Sep 13 2002 - 16:29:21 EST


Hi!

> > /*
> > * Try to free as much memory as possible, but do not OOM-kill anyone
> > *
> > * Notice: all userland should be stopped at this point, or livelock
> > is possible.
> > */
> >
> > This worked before -rmap came in, but it does not free anything
> > now. What needs to be done to fix it?
>
> Actually, it still worked when -rmap came in, but it stopped working
> when the LRU lists were made to be per-zone...
>
> > static void free_some_memory(void)
> > {
> > printk("Freeing memory: ");
> > while
> > (try_to_free_pages(&contig_page_data.node_zones[ZONE_HIGHMEM], GFP_KSWAPD, 0))
> > printk(".");
> > printk("|\n");
> > }
>
> Why don't you just allocate memory ?
>
> To prevent the OOM kill you can just check for a variable
> in the OOM slow path. No need to rely on any particular
> behaviour of the VM.

Allocating memory is pain because I have to free it afterwards. Yep I
have such code, but it is ugly. try_to_free_pages() really seems like
cleaner solution to me... if you only tell me how to fix it :-).

If it is not easy to fix, I can reintroduce memory eating code; but
I'd hate to special-case SWSUSP in VM. Otoh GFP_FAIL or something like
that might help me, right?
                                                                Pavel

-- 
Casualities in World Trade Center: ~3k dead inside the building,
cryptography in U.S.A. and free speech in Czech Republic.
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