On Mon, Feb 13, 2006, Andrew Morton wrote:
> Johannes Stezenbach <js@linuxtv.org> wrote:
> > Now copying a 700MB file makes "Dirty" go up to 350MB. It then
> > slowly decreases to 325MB and stays there.
> 
> It shouldn't.  Did you really leave it for long enough?
> 
> If you did, then why does it happen there and not here?

Good question. I just repeated the execise, rebooted and
copied a 700MB file. After ~30min "Dirty" is down to ~130MB, and
continues to decrease very slowly.

On my Desktop machine (P4 HT, 1G RAM) "Dirty" goes down near
zero after ~30sec, as expected.

Here's some output from sysctl -a (should all be default values,
I did not mess with any of those setting but I'm not sure what
Debian does behind my back):

vm.swap_token_timeout = 300
vm.legacy_va_layout = 0
vm.vfs_cache_pressure = 100
vm.block_dump = 0
vm.laptop_mode = 0
vm.max_map_count = 65536
vm.min_free_kbytes = 3831
vm.lowmem_reserve_ratio = 256   256     32
vm.swappiness = 60
vm.nr_pdflush_threads = 2
vm.dirty_expire_centisecs = 3000
vm.dirty_writeback_centisecs = 500
vm.dirty_ratio = 40
vm.dirty_background_ratio = 10
vm.page-cluster = 3
vm.overcommit_ratio = 50
vm.overcommit_memory = 0

.config and dmesg output attached.

Let me know if I can do more tests to find out what's going on.


Johannes