* Greg Smith: > Note the comment from the first article saying "those delays can be 30 > seconds or more". On multiple occasions, I've measured systems with > dozens of disks in a high-performance RAID1+0 with battery-backed > controller that could grind to a halt for 10, 20, or more seconds in > this situation, when running pgbench on a big database. We see that quite a bit, too (we're still on ext3, mostly 2.6.26ish kernels). It seems that the most egregious issues (which even trigger the two minute kernel hangcheck timer) are related to CFQ. We don't see it on systems we have switched to the deadline I/O scheduler. But data on this is a bit sketchy. -- Florian Weimer <fweimer@xxxxxx> BFK edv-consulting GmbH http://www.bfk.de/ Kriegsstraße 100 tel: +49-721-96201-1 D-76133 Karlsruhe fax: +49-721-96201-99 -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
