Re: CPU spikes and transactions

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?

Tomas