[lkml]   [2001]   [Aug]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH][RFC] simpler __alloc_pages{_limit}
On Saturday den 25 August 2001 13:55, Stephan von Krawczynski wrote:
> On Sat, 25 Aug 2001 02:48:28 +0200
> Roger Larsson <> wrote:
> > Hi again,
> >
> > [two typos corrected from the version at linux-mm]
> > [...]
> > Doing this - the code started to collaps...
> > __alloc_pages_limit could suddenly handle all special cases!
> > (with small functional differences)
> >
> > Comments?
> Hi Roger,
> I tested your page against straight 2.4.9 (where it applied mostly, the
> rest I did manually) and experience the following:
> 1) system gets slow, even in times where plenty of free memory is
> available. There must be some overhead inside.

It is not unlikely because it care too much about the higher order
allocations. It needs a higher order page and really tries...

> 2) It does not really work around the basic problem of too
> many cached pages in case of heavy filesystem action, I do get the already
> known "kernel: __alloc_pages: 2-order allocation failed." by simply copying
> files a lot.

Is this with raiserfs and/or nfs? And without highmem support?
Why is 2-order allocations needed???
Can anyone answer?
Higher order allocs during normal operation is not that nice...

> 3) Even in high load situations the CPU load seems to get
> worse, I made it up to 7 with normal file copying on a SMP 1GHz 1GB RAM
> machine.

Might also be related to the higher order. Freeing too much inactive pages
to satisfy the request...
SMP might be a factor since the patch will go harder on the locks...

> Hm, I guess that doesn't really work as you expected.

Well, I make a version that gives up on higher order allocations more

But the real problem might be - why are the higher order allocations
needed anyway?


Roger Larsson
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 12:58    [from the cache]
©2003-2014 Jasper Spaans. hosted at Digital Ocean