On Mon, Oct 14, 2013 at 6:45 PM, Tomas Vondra <tv@xxxxxxxx> wrote: > On 15.10.2013 01:26, Tony Kay wrote: >> Hi Calvin, >> >> Yes, I have sar data on all systems going back for years. >> >> Since others are going to probably want to be assured I am really >> "reading the data" right: >> >> - This is 92% user CPU time, 5% sys, and 1% soft >> - On some of the problems, I _do_ see a short spike of pgswpout's >> (memory pressure), but again, not enough to end up using much system time >> - The database disks are idle (all data being used is in RAM)..and are >> SSDs....average service times are barely measurable in ms. > > OK. Can you share the data? Maybe we'll notice something suspicious. > >> If I had to guess, I'd say it was spinlock misbehavior....I cannot >> understand why ekse a transaction blocking other things would drive >> the CPUs so hard into the ground with user time. > > Have you tried running perf, to verify the time is actually spent on > spinlocks? +1 this. It is almost certainly spinlocks, but we need to know which one and why. plz install debug symbols and run a perf during normal and high load conditions. merlin -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
