On Tue, Mar 15, 2016 at 09:54:06AM -0400, Austin S. Hemmelgarn wrote:

On 2016-03-15 09:46, Marc Haber wrote:

quoted

On Tue, Mar 15, 2016 at 11:52:30AM +0100, Holger Hoffstätte wrote:

quoted

On 03/14/16 21:13, Marc Haber wrote:

quoted

Do I need to wait for clear_cache to finish, like until I see disk
usage dropping?

The cache isn't that big, so you won't see a huge drop. Just use the
disk normally for a few minutes, after some time the cache will be
written out again.

Is it necessary to actually cause activity on the file system or is it
ok to just let it sit there for an hour or so?

It should be OK to just let it sit there for ten or fifteen minutes. I'm
pretty certain that the free space cache gets rebuilt relatively quickly,
and I'm almost 100% certain that the old one gets dropped within seconds of
the FS being mounted with -o clear_cache.  I've rebuilt the cache on the 64G
root filesystem on my laptop a couple of times before, and it consistently
appears to take about 2-3 minutes to do so at most (based on disk usage from
the kernel itself).

In my case, atop has not seen any notable disk activity after mounting
with -o clerar_cache.

Greetings
Marc

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