Re: Occasional giant spikes in CPU load

От: Tom Lane
Тема: Re: Occasional giant spikes in CPU load
Дата: ,
Msg-id: 10446.1270685931@sss.pgh.pa.us
(см: обсуждение, исходный текст)
Ответ на: Re: Occasional giant spikes in CPU load  (Craig James)
Список: pgsql-performance

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indexes in partitioned tables - again  (Samuel Gendler, )
 Re: indexes in partitioned tables - again  (Robert Haas, )
  Occasional giant spikes in CPU load  (Craig James, )
   Re: Occasional giant spikes in CPU load  ("Joshua D. Drake", )
    Re: Occasional giant spikes in CPU load  (Craig James, )
     Re: Occasional giant spikes in CPU load  ("Joshua D. Drake", )
      Re: Occasional giant spikes in CPU load  (Craig James, )
       Re: Occasional giant spikes in CPU load  (David Rees, )
       Re: Occasional giant spikes in CPU load  (Tom Lane, )
       Re: Occasional giant spikes in CPU load  (Alan Hodgson, )
     Re: Occasional giant spikes in CPU load  ("Joshua D. Drake", )
   Re: Occasional giant spikes in CPU load  (Greg Smith, )
   Re: Occasional giant spikes in CPU load  (Tom Lane, )
    Re: Occasional giant spikes in CPU load  (Craig James, )
     Re: Occasional giant spikes in CPU load  (Steve Crawford, )
   Re: Occasional giant spikes in CPU load  (David Rees, )
    Re: Occasional giant spikes in CPU load  (Robert Haas, )
     Re: Occasional giant spikes in CPU load  (Craig James, )
      Re: Occasional giant spikes in CPU load  (David Rees, )
       Re: Occasional giant spikes in CPU load  (Robert Haas, )
        Re: Occasional giant spikes in CPU load  (Craig James, )
         Re: Occasional giant spikes in CPU load  ("Joshua D. Drake", )
         Re: Occasional giant spikes in CPU load  (Greg Smith, )
         Re: Occasional giant spikes in CPU load  (Tom Lane, )
          Re: Occasional giant spikes in CPU load  (Craig James, )
           Re: Occasional giant spikes in CPU load  (Tom Lane, )
            Re: Occasional giant spikes in CPU load  (Craig James, )
             Re: Occasional giant spikes in CPU load  ("Kevin Grittner", )
              Re: Occasional giant spikes in CPU load  (Craig James, )
             Re: Occasional giant spikes in CPU load  (Greg Smith, )
             Re: Occasional giant spikes in CPU load  (Tom Lane, )
              pgbench results on a new server  (Craig James, )
               Re: pgbench results on a new server  (Scott Marlowe, )
               Re: pgbench results on a new server  (Greg Smith, )
                Re: pgbench results on a new server  (Craig James, )
                 Re: pgbench results on a new server  (Merlin Moncure, )
                  Two fast searches turn slow when used with OR clause  (Craig James, )
                   Re: Two fast searches turn slow when used with OR clause  (Robert Haas, )
                 Re: pgbench results on a new server  (Greg Smith, )
           Re: Occasional giant spikes in CPU load  (Rajesh Kumar Mallah, )
         Re: Occasional giant spikes in CPU load  ("Joshua D. Drake", )
      Re: Occasional giant spikes in CPU load  (Bruce Momjian, )
    Re: Occasional giant spikes in CPU load  (Greg Smith, )
   Re: Occasional giant spikes in CPU load  ("Joshua D. Drake", )

Craig James <> writes:
> On 4/7/10 3:36 PM, Joshua D. Drake wrote:
>> To have your CPUs so flooded that they are the cause of an inability to
>> log in is pretty suspect.

> I thought so too, except that I can't login during the flood.  If the CPUs were all doing iowaits, logging in should
beeasy. 

> Greg's suggestion that shared_buffers and work_mem are too big for an 8 GB system fits these symptoms -- if it's
havinga swap storm, login is effectively impossible. 

Yeah, but there is also the question of what's causing all the backends
to try to run at the same time.  Oversubscribed memory could well be the
direct cause of the machine getting driven into the ground, but there's
something else going on here too IMO.

Anyway I concur with the advice to lower shared_buffers, and run fewer
backends if possible, to see if that ameliorates the problem.

            regards, tom lane


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