lkml.org 
[lkml]   [2007]   [Sep]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [00/41] Large Blocksize Support V7 (adds memmap support)
Date
Andrea Arcangeli <andrea@suse.de> writes:

> On Sat, Sep 15, 2007 at 02:14:42PM +0200, Goswin von Brederlow wrote:
>> I keep coming back to the fact that movable objects should be moved
>> out of the way for unmovable ones. Anything else just allows
>
> That's incidentally exactly what the slab does, no need to reinvent
> the wheel for that, it's an old problem and there's room for
> optimization in the slab partial-reuse logic too. Just boost the order
> 0 page size and use the slab to get the 4k chunks. The sgi/defrag
> design is backwards.

How does that help? Will slabs move objects around to combine two
partially filled slabs into nearly full one? If not consider this:

- You create a slab for 4k objects based on 64k compound pages.
(first of all that wastes you a page already for the meta infos)
- Something movable allocates a 14 4k page in there making the slab
partially filled.
- Something unmovable alloactes a 4k page making the slab mixed and
full.
- Repeat until out of memory.

OR

- Userspace allocates a lot of memory in those slabs.
- Userspace frees one in every 15 4k chunks.
- Userspace forks 1000 times causing an unmovable task structure to
appear in 1000 slabs.

MfG
Goswin
-
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/

\
 
 \ /
  Last update: 2007-09-15 22:19    [from the cache]
©2003-2011 Jasper Spaans