Re: performance on new linux box

От: Kevin Grittner
Тема: Re: performance on new linux box
Дата: ,
Msg-id: 4C35E7CC020000250003328A@gw.wicourts.gov
(см: обсуждение, исходный текст)
Ответ на: Re: performance on new linux box  (Ryan Wexler)
Список: pgsql-performance

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performance on new linux box  (Ryan Wexler, )
 Re: performance on new linux box  (Tom Lane, )
 Re: performance on new linux box  (Rob Wultsch, )
 Re: performance on new linux box  (Andy Colson, )
  Re: performance on new linux box  (Eliot Gable, )
   Re: performance on new linux box  ("Kevin Grittner", )
    Re: performance on new linux box  (Eliot Gable, )
     Re: performance on new linux box  ("Kevin Grittner", )
      Re: performance on new linux box  (Ryan Wexler, )
       Re: performance on new linux box  ("Joshua D. Drake", )
       Re: performance on new linux boxeradmin(11983)i: STATEMENT: update license set expires= '2010-06-15' where lic  (John Rouillard, )
       Re: performance on new linux box  (Craig James, )
       Re: performance on new linux box  (Russell Smith, )
        Re: performance on new linux box  (Samuel Gendler, )
         Re: performance on new linux box  (Ryan Wexler, )
          Re: performance on new linux box  (Greg Smith, )
          Re: performance on new linux box  (Andy Colson, )
       Re: performance on new linux box  ("Joshua D. Drake", )
 Re: performance on new linux box  ("Pierre C", )
 Fwd: performance on new linux box  (Ryan Wexler, )
  Re: performance on new linux box  (Jochen Erwied, )
   Re: performance on new linux box  (Ryan Wexler, )
    Re: performance on new linux box  ("Kevin Grittner", )
    Re: performance on new linux box  (Jochen Erwied, )
     Re: performance on new linux box  (Ryan Wexler, )
      Re: performance on new linux box  (Ben Chobot, )
      Re: performance on new linux box  ("Kevin Grittner", )
       Re: performance on new linux box  (Ryan Wexler, )
        Re: performance on new linux box  (David Boreham, )
        Re: performance on new linux box  ("Kevin Grittner", )
        Re: performance on new linux box  (Craig James, )
         Re: performance on new linux box  (<>, )
          Re: performance on new linux box  (Craig James, )
           Re: performance on new linux box  (Scott Carey, )
            Re: performance on new linux box  (Ben Chobot, )
             Re: performance on new linux box  (Scott Carey, )
              Re: performance on new linux box  (Ben Chobot, )
               Re: performance on new linux box  (Ryan Wexler, )
                Re: performance on new linux box  (Ben Chobot, )
                 Re: performance on new linux box  (Craig Ringer, )
               Re: performance on new linux box  (Scott Carey, )
                Re: performance on new linux box  (Ben Chobot, )
                Re: performance on new linux box  (Greg Smith, )
              Re: performance on new linux box  (Scott Marlowe, )
               Re: performance on new linux box  (Scott Carey, )
               Re: performance on new linux box  (Craig Ringer, )
            Re: performance on new linux box  (Ryan Wexler, )
          Re: performance on new linux box  (David Boreham, )
   Re: performance on new linux box  (Ryan Wexler, )
    Re: performance on new linux box  (Jochen Erwied, )
 Re: performance on new linux box  (Ben Chobot, )
  Re: performance on new linux box  ("Pierre C", )

Ryan Wexler <> wrote:

> It still amazes me that it would account for a 5x change in IO.

If you were doing one INSERT per database transaction, for instance,
that would not be at all surprising.  If you were doing one COPY in
of a million rows, it would be a bit more surprising.

Each COMMIT of a database transaction, without caching, requires
that you wait for the disk to rotate around to the right position.
Compared to the speed of RAM, that can take quite a long time.  With
write caching, you might write quite a few adjacent disk sectors to
the cache, which can then all be streamed to disk on one rotation.
It can also do tricks like writing a bunch of sectors on one part of
the disk before pulling the heads all the way over to another
portion of the disk to write a bunch of sectors.

It is very good for performance to cache writes.

-Kevin


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Сообщение: Re: Need help in performance tuning.