Re: New file system with same issue

[Marc Haber <mh+linux-btrfs@zugschlus.de>]

On Tue, Mar 15, 2016 at 09:54:06AM -0400, Austin S. Hemmelgarn wrote:
> On 2016-03-15 09:46, Marc Haber wrote:
> >On Tue, Mar 15, 2016 at 11:52:30AM +0100, Holger Hoffstätte wrote:
> >>On 03/14/16 21:13, Marc Haber wrote:
> >>>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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