RE: Where is the performance bottleneck?

From: Guy (bugzilla_at_watkins-home.com)
Date: 08/31/05

  • Next message: Luck, Tony: "RE: [PATCH] Only process_die notifier in ia64_do_page_fault if KPROBES is configured." 
    To: "'Holger Kiehl'" <Holger.Kiehl@dwd.de>, "'Mark Hahn'" <hahn@physics.mcmaster.ca>
Date:	Tue, 30 Aug 2005 19:05:32 -0400

    In most of your results, your CPU usage is very high. Once you get to about
    90% usage, you really can't do much else, unless you can improve the CPU
    usage.

    Guy

    > -----Original Message-----
    > From: linux-raid-owner@vger.kernel.org [mailto:linux-raid-
    > owner@vger.kernel.org] On Behalf Of Holger Kiehl
    > Sent: Tuesday, August 30, 2005 3:09 PM
    > To: Mark Hahn
    > Cc: linux-raid; linux-kernel
    > Subject: Re: Where is the performance bottleneck?
    >
    > On Mon, 29 Aug 2005, Mark Hahn wrote:
    >
    > >> The U320 SCSI controller has a 64 bit PCI-X bus for itself, there is no
    > other
    > >> device on that bus. Unfortunatly I was unable to determine at what
    > speed
    > >> it is running, here the output from lspci -vv:
    > > ...
    > >> Status: Bus=2 Dev=4 Func=0 64bit+ 133MHz+ SCD- USC-,
    > DC=simple,
    > >
    > > the "133MHz+" is a good sign. OTOH the latency (72) seems rather low -
    > my
    > > understanding is that that would noticably limit the size of burst
    > transfers.
    > >
    > I have tried with 128 and 144, but the transfer rate is only a little
    > bit higher barely measurable. Or what values should I try?
    >
    > >
    > >> Version 1.03 ------Sequential Output------ --Sequential Input-
    > --Random-
    > >> -Per Chr- --Block-- -Rewrite- -Per Chr- --Block--
    > --Seeks--
    > >> Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP
    > /sec %CP
    > >> Raid0 (8 disk)15744M 54406 96 247419 90 100752 25 60266 98 226651 29
    > 830.2 1
    > >> Raid0s(4 disk)15744M 54915 97 253642 89 73976 18 59445 97 198372 24
    > 659.8 1
    > >> Raid0s(4 disk)15744M 54866 97 268361 95 72852 17 59165 97 187183 22
    > 666.3 1
    > >
    > > you're obviously saturating something already with 2 disks. did you
    > play
    > > with "blockdev --setra" setings?
    > >
    > Yes, I did play a little bit with it but this only changed read
    > performance,
    > it made no measurable difference when writting.
    >
    > Thanks,
    > Holger
    >
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