gnome-calendar opens /usr/share/zoneinfo/* every 30 seconds

[Colin Ian King]

I've been trying to figure out why my HDD keeps on flushing metadata out every minute on an idle laptop and discovered that gnome-calendar opens /usr/share/zoneinfo/Europe/London on my machine every minute. This causes the access time (atime) to be updated causing a metadata flush afterwards. On an idle laptop this makes the HDD spin up, write data and then spin down again. This consumes power.

Can this periodic open/closing be fixed or at least try to use O_NOATIME on the opening to reduce the metadata atime updates?

I diagnosed this by running:

sudo fnotifystat -v -x/sys,/proc,/home

one can see that the gnome-calendar is opening and closing the file.

Looking deeper, I used health-check on gnome-calendar to gather the attached activity log of 5 minutes of activity of gnome-calendar on the idle machine. One can see it sleeps for ~60 seconds on a poll() system call and every 60 seconds opens and closes the zoneinfo file.

To capture the activity I used:

sudo health-check -p gnome-calendar -d 300 -f -r -v > gnome-calendar-5min.log

I'm pretty sure that opening the zoneinfo file with O_NOATIME will avoid the metadata atime flushes and because the data has not changed on disk it should avoid the HDD spinup/spindown cycling. Alternatively, can the zoneinfo reads be avoided totally every 60 seconds to save power?

[Colin Ian King (colin-king)]

Oh, actually, it was doing 10 accesses in 300 seconds, so it's polling every 30 seconds, higher than I first thought.