From: Andrew Morton <akpm@digeo.com>
To: Rik van Riel <riel@conectiva.com.br>
Cc: Pavel Machek <pavel@ucw.cz>, kernel list <linux-kernel@vger.kernel.org>
Subject: Re: Good way to free as much memory as possible under 2.5.34?
Date: Fri, 13 Sep 2002 14:30:47 -0700 [thread overview]
Message-ID: <3D825907.493B4DB3@digeo.com> (raw)
In-Reply-To: Pine.LNX.4.44L.0209131808240.1857-100000@imladris.surriel.com
Rik van Riel wrote:
>
> On Fri, 13 Sep 2002, Pavel Machek wrote:
>
> > /*
> > * 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...
hmm, I missed that. Yes, the zone balancing in try_to_free_pages() will
see that all zones are above ->pages_high and will just return.
> > 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 ?
That would work.
> 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.
>
Sure.
I'm not sure why swsusp needs "half of memory to be free"? What's
the story there?
I'd recommend that you sit in a loop, allocating pages with an
allocation mode of
__GFP_HIGHMEM | __GFP_WAIT
This will give you all the easily-reclaimable pages in the machine,
without trashing the page reserves (no __GFP_HIGH).
String all the pages together via page->list and when you have "enough",
free them all again.
prev parent reply other threads:[~2002-09-13 21:26 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-13 21:00 Good way to free as much memory as possible under 2.5.34? Pavel Machek
2002-09-13 21:09 ` Rik van Riel
2002-09-13 21:29 ` Pavel Machek
2002-09-13 21:33 ` Rik van Riel
2002-09-13 21:48 ` Xavier Bestel
2002-09-13 22:42 ` Rik van Riel
2002-09-13 23:26 ` Xavier Bestel
2002-09-13 21:53 ` Andrew Morton
2002-09-13 22:10 ` William Lee Irwin III
2002-09-14 10:05 ` Pavel Machek
2002-09-14 13:57 ` Andrew Morton
2002-09-14 14:51 ` Hans-Peter Jansen
2002-09-14 15:07 ` Rik van Riel
2002-09-14 15:11 ` Pavel Machek
2002-09-13 21:30 ` Andrew Morton [this message]
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