Re[2]: ARC "pressured out", how to control/stabilize ? (reformatted to text/plain)

From: Vladimir Sharun <atz_at_ukr.net>
Date: Mon, 06 Jan 2014 13:14:52 +0200

('binary' encoding is not supported, stored as-is) Dear Andriy and FreeBSD community, I got the few minutes run for this dtrace hook; here's the output for 15 minutes run: http://pastebin.com/pKm9kLwa Does it explain something ? > on 04/01/2014 14:50 Vladimir Sharun said the following: > [snip] > > ARC: 28G Total, 2085M MFU, 20G MRU, 29M Anon, 1858M Header, 3855M Other > [snip] > > ITEM SIZE LIMIT USED FREE REQ FAIL SLEEP > [snip] > > zio_data_buf_131072: 131072, 0, 488217, 9,287155442, 0, 0 > > I noticed a particular discrepancy between reported ARC usage and sizes of UMA > zones used by ZFS code: > > 488217 * 131072 = ~59GB right there. > > There are several possibilities for this discrepancy: > - bad accounting or reporting of ARC stats > - those 128K buffers being used in a special way and thus not accounted as ARC > - some sort of resource leak > > You could try to use DTrace to gather the stacks of all code paths that lead to > allocation of those buffers. Something like: > > fbt::zio_data_buf_alloc:entry > /arg0 == 131072/ > { > _at_[stack()] = count(); > } > > This could be a start for understanding the issue. > Received on Mon Jan 06 2014 - 10:15:05 UTC