Re: Scalability in postgres

От: Kevin Grittner
Тема: Re: Scalability in postgres
Дата: ,
Msg-id: 4A28057B0200002500027598@gw.wicourts.gov
(см: обсуждение, исходный текст)
Ответ на: Re: Scalability in postgres  (James Mansion)
Список: pgsql-performance

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Scalability in postgres  (Fabrix, )
 Re: Scalability in postgres  (David Rees, )
  Re: Scalability in postgres  (Fabrix, )
   Re: Scalability in postgres  (Scott Mead, )
    Re: Scalability in postgres  (Fabrix, )
   Re: Scalability in postgres  (Scott Marlowe, )
 Re: Scalability in postgres  (Scott Marlowe, )
  Re: Scalability in postgres  (Fabrix, )
  Re: Scalability in postgres  (Flavio Henrique Araque Gurgel, )
   Re: Scalability in postgres  (Fabrix, )
    Re: Scalability in postgres  (Scott Marlowe, )
    Re: Scalability in postgres  (Flavio Henrique Araque Gurgel, )
     Re: Scalability in postgres  (Greg Smith, )
      Re: Scalability in postgres  (Grzegorz Jaśkiewicz, )
       Re: Scalability in postgres  (Scott Marlowe, )
       Re: Scalability in postgres  (Scott Marlowe, )
        Re: Scalability in postgres  (Grzegorz Jaśkiewicz, )
         Re: Scalability in postgres  (Scott Marlowe, )
          Re: Scalability in postgres  (Grzegorz Jaśkiewicz, )
           Re: Scalability in postgres  (Scott Marlowe, )
            Re: Scalability in postgres  (Grzegorz Jaśkiewicz, )
             Re: Scalability in postgres  (Scott Marlowe, )
         Re: Scalability in postgres  (Ron Mayer, )
       Re: Scalability in postgres  (Greg Smith, )
        Re: Scalability in postgres  (Scott Mead, )
         Re: Scalability in postgres  (Scott Marlowe, )
         Re: Scalability in postgres  (Fabrix, )
          Re: Scalability in postgres  (Scott Mead, )
      Re: Scalability in postgres  (Fabrix, )
       Re: Scalability in postgres  (Greg Smith, )
      Re: Scalability in postgres  (Scott Carey, )
       Re: Scalability in postgres  (Greg Smith, )
        Re: Scalability in postgres  (Scott Marlowe, )
         Re: Scalability in postgres  (Greg Smith, )
       Re: Scalability in postgres  (Fabrix, )
        Re: Scalability in postgres  (Scott Carey, )
      Re: Scalability in postgres  (James Mansion, )
       Re: Scalability in postgres  ("Kevin Grittner", )
        Re: Scalability in postgres  (Dimitri, )
         Re: Scalability in postgres  ("Kevin Grittner", )
          Re: Scalability in postgres  (Scott Carey, )
           Re: Scalability in postgres  (Robert Haas, )
            Re: Scalability in postgres  (Scott Carey, )
             Re: Scalability in postgres  (Robert Haas, )
              Re: Scalability in postgres  (Scott Carey, )
               Re: Scalability in postgres  (Robert Haas, )
              Re: Scalability in postgres  (, )
               Re: Scalability in postgres  (Robert Haas, )
                Re: Scalability in postgres  (Greg Smith, )
                 Re: Scalability in postgres  (, )
                  Re: Scalability in postgres  (Robert Haas, )
                 Re: Scalability in postgres  (Mark Mielke, )
                  Re: Scalability in postgres  (Greg Smith, )
                   Re: Scalability in postgres  (Robert Haas, )
                 Re: Scalability in postgres  (Craig James, )
          Re: Scalability in postgres  (Dimitri, )
           Re: Scalability in postgres  (Marc Cousin, )
        Re: Scalability in postgres  (James Mansion, )
         Re: Scalability in postgres  ("Kevin Grittner", )
          Re: Scalability in postgres  (Mark Mielke, )
           Re: Scalability in postgres  (, )
            Re: Scalability in postgres  (Mark Mielke, )
             Re: Scalability in postgres  (, )
           Re: Scalability in postgres  ("Kevin Grittner", )
           Re: Scalability in postgres  (Greg Smith, )
          Re: Scalability in postgres  (Scott Carey, )
           Re: Scalability in postgres  ("Kevin Grittner", )
         Re: Scalability in postgres  ("Kevin Grittner", )
 Re: Scalability in postgres  (Jeff Janes, )
  Re: Scalability in postgres  (Tom Lane, )
   Re: Scalability in postgres  (Jeff Janes, )
  Re: Scalability in postgres  ("", )

James Mansion <> wrote:

>> they spend a lot of time spinning around queue access to see if
>> anything has become available to do -- which causes them not to
>> play nice with other processes on the same box.

> UNIX systems have routinely managed large numbers of runnable
> processes where the run queue lengths are long without such an
> issue.

Hmmm...  Did you think the queues I mentioned where OS run queues?  In
case that's a source of misunderstanding, let me clarify.

Sybase ASE (and derivatives) have a number of queues to schedule work.
When something needs doing, it's put on a queue.  The "engines" cycle
through checking these queues for work, using non-blocking methods for
I/O where possible.  There is a configurable parameter for how many
times an engine should check all queues without finding any work to do
before it voluntarily yields its CPU.  This number was always a tricky
one to configure, as it would starve other processes on the box if set
too high, and would cause the DBMS to context switch too much if set
too low.  Whenever a new release came out, or we changed the other
processes running on a database server, we had to benchmark to see
where the "sweet spot" was.  We ranged from 16 to 20000 for this value
at various times.

Those are the queues I meant.

-Kevin


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