Re: CPU causes 100% load in user space when ntp client runs and postgresql is under heavy load

On 09/24/2012 03:53 PM, Dennis Brouwer wrote:

> Last week I was repeatedly able to run all these tests on the database
> without any issue but recently, all of a sudden at random, some of the
> queries performed a factor 100 less. It may take hours to complete the
> transaction. At the same moment we see a dramatic decrease in IO and the
> CPU is nearly 100% busy in user space.
>
> After days of testing I may have found the cause: the ntp client. If I stop
> the ntp client the problem vanishes.

Any chance you are hitting this known linux bug in conjunction with a
misconfigured ntp server? ie. does a

  # date -s now

fix the cpu load?



http://blog.mozilla.org/it/2012/06/30/mysql-and-the-leap-second-high-cpu-and-the-fix/comment-page-1/#comment-1471



http://serverfault.com/questions/403732/anyone-else-experiencing-high-rates-of-linux-server-crashes-during-a-leap-second



--
Marcello Perathoner
webmaster@gutenberg.org