Re: How to improve db performance with $7K?

From: PFC
Subject: Re: How to improve db performance with $7K?
Date: ,
Msg-id: op.so9qe5y2th1vuj@localhost
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In response to: Re: How to improve db performance with $7K?  (Alex Turner)
Responses: Re: How to improve db performance with $7K?  (Alan Stange)
List: pgsql-performance

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How to improve db performance with $7K?  (Steve Poe, )
 Re: How to improve db performance with $7K?  (Tom Lane, )
  Re: How to improve db performance with $7K?  (Steve Poe, )
 Re: How to improve db performance with $7K?  (Will LaShell, )
 Re: How to improve db performance with $7K?  ("Joshua D. Drake", )
  Re: How to improve db performance with $7K?  (Steve Poe, )
   Re: How to improve db performance with $7K?  (Bjoern Metzdorf, )
    Re: How to improve db performance with $7K?  (Josh Berkus, )
     Re: How to improve db performance with $7K?  (Steve Poe, )
      Re: How to improve db performance with $7K?  (Cott Lang, )
       Re: How to improve db performance with $7K?  (Steve Poe, )
        Re: How to improve db performance with $7K?  (Cott Lang, )
         Follow-Up: How to improve db performance with $7K?  (Steve Poe, )
          Re: Follow-Up: How to improve db performance with $7K?  (Thomas F.O'Connell, )
           Re: Follow-Up: How to improve db performance with $7K?  (Kevin Brown, )
            Re: Follow-Up: How to improve db performance with $7K?  ("Steinar H. Gunderson", )
            Re: Follow-Up: How to improve db performance with $7K?  (Thomas F.O'Connell, )
          Re: Follow-Up: How to improve db performance with $7K?  (Vivek Khera, )
           Re: Follow-Up: How to improve db performance with $7K?  (Will LaShell, )
     Re: How to improve db performance with $7K?  (Steve Poe, )
    Re: Follow-Up: How to improve db performance with $7K?  (PFC, )
     Re: Follow-Up: How to improve db performance with $7K?  ("Steinar H. Gunderson", )
   Re: How to improve db performance with $7K?  (PFC, )
    Re: How to improve db performance with $7K?  (Dave Cramer, )
     Re: How to improve db performance with $7K?  (Greg Stark, )
     Re: How to improve db performance with $7K?  (Alex Turner, )
      Re: How to improve db performance with $7K?  (Steve Poe, )
       Re: How to improve db performance with $7K?  (Alex Turner, )
        Re: How to improve db performance with $7K?  (Vivek Khera, )
         Re: How to improve db performance with $7K?  (Alex Turner, )
        Re: How to improve db performance with $7K?  (William Yu, )
         Re: How to improve db performance with $7K?  (Alex Turner, )
          Re: How to improve db performance with $7K?  (William Yu, )
           Re: How to improve db performance with $7K?  (Alex Turner, )
            Re: How to improve db performance with $7K?  ("Jim C. Nasby", )
             Re: How to improve db performance with $7K?  (Alex Turner, )
              Re: How to improve db performance with $7K?  (Alex Turner, )
               Re: How to improve db performance with $7K?  (Alex Turner, )
              Re: How to improve db performance with $7K?  (Greg Stark, )
               Re: How to improve db performance with $7K?  (Alex Turner, )
               Re: How to improve db performance with $7K?  (Tom Lane, )
                Re: How to improve db performance with $7K?  (Kevin Brown, )
                 Re: How to improve db performance with $7K?  (Greg Stark, )
                  Re: How to improve db performance with $7K?  (Kevin Brown, )
                   Re: How to improve db performance with $7K?  (Tom Lane, )
                    Re: How to improve db performance with $7K?  (Kevin Brown, )
                     Re: How to improve db performance with $7K?  (Alex Turner, )
                      Re: How to improve db performance with $7K?  (PFC, )
                     Re: How to improve db performance with $7K?  (Tom Lane, )
                      Re: How to improve db performance with $7K?  (Kevin Brown, )
                       Re: How to improve db performance with $7K?  (Tom Lane, )
                        Re: How to improve db performance with $7K?  (Kevin Brown, )
                      Re: How to improve db performance with $7K?  (Greg Stark, )
                     Re: How to improve db performance with $7K?  (Vivek Khera, )
                      Re: How to improve db performance with $7K?  ("Joshua D. Drake", )
                       Re: How to improve db performance with $7K?  (Vivek Khera, )
                      Re: How to improve db performance with $7K?  (Kevin Brown, )
                    Re: How to improve db performance with $7K?  (Matthew Nuzum, )
                     Re: How to improve db performance with $7K?  ("Jim C. Nasby", )
                   Re: How to improve db performance with $7K?  (Rosser Schwarz, )
                    Re: How to improve db performance with $7K?  (Kevin Brown, )
                   Re: How to improve db performance with $7K?  (Greg Stark, )
                   Re: How to improve db performance with $7K?  (Bruce Momjian, )
                    Re: How to improve db performance with $7K?  (Alex Turner, )
                     Re: How to improve db performance with $7K?  (Alvaro Herrera, )
                     Re: How to improve db performance with $7K?  (Bruce Momjian, )
              Re: How to improve db performance with $7K?  ("Douglas J. Trainor", )
               Re: How to improve db performance with $7K?  (, )
                Re: How to improve db performance with $7K?  (Alex Turner, )
                 Re: How to improve db performance with $7K?  (, )
            Re: How to improve db performance with $7K?  ("Douglas J. Trainor", )
            Re: How to improve db performance with $7K?  (PFC, )
             Re: How to improve db performance with $7K?  (Alan Stange, )
    Re: How to improve db performance with $7K?  (Dave Cramer, )
 Re: How to improve db performance with $7K?  ("Alexander Kirpa", )
 Re: How to improve db performance with $7K?  ("Mohan, Ross", )
 Re: How to improve db performance with $7K?  ("Matthew Nuzum", )
  Re: How to improve db performance with $7K?  (Greg Stark, )
   Re: How to improve db performance with $7K?  (PFC, )
  Re: How to improve db performance with $7K?  (Tom Lane, )
 Re: How to improve db performance with $7K?  ("Dave Held", )
 Re: How to improve db performance with $7K?  ("Mohan, Ross", )
  Re: How to improve db performance with $7K?  (Steve Poe, )
   Re: How to improve db performance with $7K?  ("Joshua D. Drake", )
   Re: How to improve db performance with $7K?  (William Yu, )
    Re: How to improve db performance with $7K?  (Greg Stark, )
     Re: How to improve db performance with $7K?  (Alex Turner, )
      Re: How to improve db performance with $7K?  (Greg Stark, )
       Re: How to improve db performance with $7K?  (Alex Turner, )
        Re: How to improve db performance with $7K?  (Jacques Caron, )
         Re: How to improve db performance with $7K?  (Alex Turner, )
          Re: How to improve db performance with $7K?  (Alex Turner, )
           Re: How to improve db performance with $7K?  (Jacques Caron, )
            Re: How to improve db performance with $7K?  (Alex Turner, )
          Re: How to improve db performance with $7K?  (Jacques Caron, )
         Re: How to improve db performance with $7K?  (Greg Stark, )
        Re: How to improve db performance with $7K?  (Alan Stange, )
        Re: How to improve db performance with $7K?  (John A Meinel, )
         Re: How to improve db performance with $7K?  (Alex Turner, )
          Re: How to improve db performance with $7K?  ("Joshua D. Drake", )
           Re: How to improve db performance with $7K?  (Alex Turner, )
        Re: How to improve db performance with $7K?  (Steve Poe, )
         Re: How to improve db performance with $7K?  (Alex Turner, )
     Re: How to improve db performance with $7K?  (Jacques Caron, )
      Re: How to improve db performance with $7K?  ("Jim C. Nasby", )
     Re: How to improve db performance with $7K?  (William Yu, )
 Re: How to improve db performance with $7K?  ("Dave Held", )
 Re: How to improve db performance with $7K?  ("Mohan, Ross", )
 Re: How to improve db performance with $7K?  ("Dave Held", )
  Re: How to improve db performance with $7K?  ("Jim C. Nasby", )
 Re: How to improve db performance with $7K?  ("Mohan, Ross", )
  Re: How to improve db performance with $7K?  ("Jim C. Nasby", )
   Re: How to improve db performance with $7K?  (Alex Turner, )
 Re: How to improve db performance with $7K?  ("Dave Held", )
  Re: How to improve db performance with $7K?  (Alex Turner, )
   Re: How to improve db performance with $7K?  (William Yu, )
 Re: How to improve db performance with $7K?  ("Mohan, Ross", )
  Re: How to improve db performance with $7K?  (Bruce Momjian, )
   Re: How to improve db performance with $7K?  (, )
    Re: How to improve db performance with $7K?  ("Jim C. Nasby", )
     What to do with 6 disks?  (Jeff Frost, )
      Re: What to do with 6 disks?  ("Jim C. Nasby", )
      Re: What to do with 6 disks?  (Josh Berkus, )
       Re: Opteron vs Xeon (Was: What to do with 6 disks?)  (Jeff Frost, )
        Re: Opteron vs Xeon (Was: What to do with 6 disks?)  ("J. Andrew Rogers", )
         Re: Opteron vs Xeon (Was: What to do with 6 disks?)  (Jeff Frost, )
          Re: Opteron vs Xeon (Was: What to do with 6 disks?)  (William Yu, )
        Re: Opteron vs Xeon (Was: What to do with 6 disks?)  (Vivek Khera, )
       Re: What to do with 6 disks?  (Vivek Khera, )
      Re: What to do with 6 disks?  (William Yu, )
 Re: How to improve db performance with $7K?  ("Mohan, Ross", )
  Re: How to improve db performance with $7K?  (Bruce Momjian, )
  Re: How to improve db performance with $7K?  (Dawid Kuroczko, )
 Re: How to improve db performance with $7K?  ("Mohan, Ross", )
 Re: How to improve db performance with $7K?  ("Mohan, Ross", )
 Re: How to improve db performance with $7K?  ("Mohan, Ross", )
 Re: How to improve db performance with $7K?  ("Dave Held", )
 Re: How to improve db performance with $7K?  ("Mohan, Ross", )


> My argument is that a sufficiently smart kernel scheduler *should*
> yield performance results that are reasonably close to what you can
> get with that feature.  Perhaps not quite as good, but reasonably
> close.  It shouldn't be an orders-of-magnitude type difference.

    And a controller card (or drive) has a lot less RAM to use as a cache /
queue for reordering stuff than the OS has, potentially the OS can us most
of the available RAM, which can be gigabytes on a big server, whereas in
the drive there are at most a few tens of megabytes...

    However all this is a bit looking at the problem through the wrong end.
The OS should provide a multi-read call for the applications to pass a
list of blocks they'll need, then reorder them and read them the fastest
possible way, clustering them with similar requests from other threads.

    Right now when a thread/process issues a read() it will block until the
block is delivered to this thread. The OS does not know if this thread
will then need the next block (which can be had very cheaply if you know
ahead of time you'll need it) or not. Thus it must make guesses, read
ahead (sometimes), etc...


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From: "Joshua D. Drake"
Date:
Subject: Re: How to improve db performance with $7K?
From: Alex Turner
Date:
Subject: Re: Intel SRCS16 SATA raid?