Re: Large slab cache in 2.6.1

Nick Piggin
2004-02-23T00:16:40Z

Andrew Morton wrote:

>Chris Wedgwood <cw@f00f.org> wrote:
>
>>On Sun, Feb 22, 2004 at 05:35:09PM +1100, Nick Piggin wrote:
>>
>>
>>>Can you maybe use this patch then, please?
>>>
>>I probably need to do more testing, but the quick patch I was using
>>against mainline (bk head) works better than this against 2.5.3-mm2.
>>
>
>The patch which went in six months or so back which said "only reclaim slab
>if we're scanning lowmem pagecache" was wrong. I must have been asleep at
>the time.
>
>We do need to scan slab in response to highmem page reclaim as well.
>Because all the math is based around the total amount of memory in the
>machine, and we know that if we're performing highmem page reclaim then the
>lower zones have no free memory.
>
>

I don't understand this. Presumably if the lower zones have no free
memory then we'll be doing lowmem page reclaim too, and that will
be shrinking the slab.

The patch I sent you should (modulo the ->seeks stuff) make it
behave as if the slab pages are on lowmem LRUs and get scanned
accordingly.