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    SubjectRe: RAID-0 read perf. decrease after 2.4.20
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    On Mon, 2003-11-24 at 02:05, Martin Knoblauch wrote:
    > >Hello All!
    > >
    > >Has anyone else experienced a drastic drop in read performance on
    > >software
    > >RAID-0 with post 2.4.20 kernels? We have a few Athlon XP's here at our
    > >lab with double IDE disks on different channels set up as RAID-0. Some
    > >bonnie++ benchmark results with various kernels, on the same machine
    > >(Athlon XP 2400+, 2 GHz, 1.5 GB RAM, VIA chipset, 2*Maxtor 120 GB
    > >6Y060L0):
    > >write read
    > >2.4.20-ac1: 88,000 135,000 K/sec
    > >2.4.21-pre7: 93,000 75,000
    > >2.4.22-ac4: 94,000 82,000
    >
    > Hi,
    >
    > I can attest a similar drop in read performance on a IA64 box going
    > from a 2.4.19ish kernel to 2.4.22. In our setup the RAID0 is LVM, not
    > MD.The RAID is used a a scratch device for a out-of-core finite element
    > program (NASTRAN).
    >
    > The setup is some 20 disks on 4 controllers. "iozone" read/reread
    > Performance went from about 400MB/sec to 260 MB/sec, while write went
    > up a notch. Unfortunatelly the read performance is more important for
    > the application in question.
    >
    > Due to the fact that I have no controll over the use of the system I
    > cannot make any experiments to find out what killed performance. Sorry
    > :-(
    >
    > Martin
    >
    > =====
    > ------------------------------------------------------
    > Martin Knoblauch
    > email: knobi@knobisoft.de or knobi@rocketmail.com
    > www: http://www.knobisoft.de
    >
    >

    And this isn't the read-ahead size change thing?

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