Re: periodic daily takes a very long time to run (14-stable)

From: Guido Falsi <mad_at_madpilot.net>
Date: Sat, 28 Oct 2023 22:42:14 UTC
On 29/10/23 00:33, void wrote:
> On Fri, Oct 27, 2023 at 05:38:58PM +0200, Guido Falsi wrote:
>> I have this for ccache FS (zfs):
>>
>> dumpster/ccache  atime                 on                     local
> 
> I wondered why you have this set to 'on'?
> 
> I mean I know /var/mail needs it for mail to function. Is it the same
> wiht ccache ?
> 

I used to have it off, but recently I turned it on. I have not really 
properly checked, but I have an hunch that ccache is using atime to 
decide which files to properly clean up the cache (LRU logic).

With atime - off you get atime = mtime, which is not the best option for 
LRU logic. You want objects to be counted as "hot" if they were 
created/modified a long time ago, but used yesterday.

Recent manual page does talk about atime, also a quick search in the 
sources reference atime multiple times. So it IS using it.

To be on the safe side, I've added this, but as I said I did this 
recently so I still don't know if it is really helping.

-- 
Guido Falsi <mad@madpilot.net>