How low can vm.vfs_cache_pressure get?

I read on the wiki article https://wiki.archlinux.org/index.php/Ma … erformance, about adjusting `vm.vfs_cache_pressure` and I did the test as suggested http://rudd-o.com/en/linux-and-free-sof … o-fix-that
sync
echo 3 > /proc/sys/vm/drop_caches
dd if=/dev/zero of=/tmp/testfile count=1 bs=900M
sysctl -w vm.vfs_cache_pressure=100
find / > /dev/null
cp /tmp/testfile /tmp/testfile2
time find / > /dev/null
sysctl -w vm.vfs_cache_pressure=50
find / > /dev/null
cp /tmp/testfile2 /tmp/testfile3
time find / > /dev/null
rm -f /tmp/testfile /tmp/testfile2 /tmp/testfile3
Then also tried lowering `vm.vfs_cache_pressure` to 20. Seems to run even faster ... slightly ... 0.1s from 50. Was wondering if its safe? I dont really understand how it works fully tho ... specifically ... whats a "inode/dentry cache"?
Last edited by jiewmeng (2012-10-19 11:33:06)

The own site seems to offer the answer to your question,
Please experiment with this value. Values close to 100 provide no gain. Values close to zero can cause huge swap activity during big filesystem scans.
From what I have further read on this it seems that setting it to 0 may lead to out-of-memory conditions.
I presume that, just like in many other things in life, it is for you to decide where the perfect/acceptable balance is trying to avoid that 'huge swap activity' if it harms your computer performance.

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How low can vm.vfs_cache_pressure get?

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