Re: Strange dcache memory pressure when highmem enabled

[Andrea Arcangeli]

On Wed, Oct 22, 2003 at 08:57:52AM +1000, Neil Brown wrote:
> I didn't end up trying Andrew's patch, but tried 2.4.23-pre7 instead.
> It appears to be doing the right thing.
> Free Highmem (grep HighFree /proc/meminfo) steadily dropped from 3Gig
> to about 2-3 Meg and stayed there.
> The dentry cache (grep dentry_cache /proc/slabinfo) climbed up to
> about 500,000 and stayed there for 24 hours - much better than before
> where it would often be only a few thousand and we had complaints every
> night when the backups ran.

sounds good. And unless I misread something Andrew's patch shrinking
lowmem only for highmem allocation definitely looks wrong and it would
be DoSable as well.

As for 2.4 mainline there's some bit of refill_inactive still not fully
classzone aware, it's the half merge bit mentioned earlier on the list
that also introduced a typo kind of bug. My tree is fully aware instead
to avoid falling apart on the 32G boxes in production. Those secondary
bits in refill_inactive should be merged in mainline too over time.

Anyways for a 1G machine (or maybe with 2G too), those bits could hardly
make any difference, I assume your highmem/lowmem ratio isn't too high.

thanks,

Andrea - If you prefer relying on open source software, check these links:
	    rsync.kernel.org::pub/scm/linux/kernel/bkcvs/linux-2.[45]/
	    http://www.cobite.com/cvsps/
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