On Mon, 15 Feb 2016, Dave Chinner wrote:
On Tue, Feb 16, 2016 at 02:58:04AM +0000, Nag Avadhanam (nag) wrote:
Its the calculation of the # of bytes of non-reclaimable file system cache
pages that has been troubling us. We do not want to count inactive file
pages (of programs/binaries) that were once mapped by any process in the
system as reclaimable because that might lead to thrashing under memory
pressure (we want to alert admins before system starts dropping text
pages).
The code presented does not match your requirements. It only counts
pages that are currently mapped into ptes. hence it will tell you
that once-used and now unmapped binary pages are reclaimable, and
drop caches will reclaim them. hence they'll need to be fetched from
disk again if they are faulted in again after a drop_caches run.
Will the inactive binary pages be automatically unmapped even if the process
into whose address space they are mapped is still around? I thought they
are left mapped until such time there is memory pressure.
We only care for binary pages (active and inactive) mapped into the address
spaces of live processes. Its okay to aggressively reclaim inactive
pages once mapped into processes that are no longer around.
thanks,
nag
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
--
To unsubscribe from this list: send the line "unsubscribe linux-doc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
