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    SubjectPoor SCSI // reading using 2.2.10-ac4 SMP


    I have run iozone locally on my new 18 Go hard disk to check performance.
    The Linux machine is a PII 400/128 Mo/SMP/Tekram 390F.

    I have quite good results with only one iozone : 17+ Mo/s writing, 15+ Mo/s

    Now, I can see really bad performance with 3 iozones running :
    17+ Mo/s (cumulated) writing, and 2,7 Mo/s (cumulated) reading. At the time
    of reading, both CPU load is nearly null.

    If I use a UP kernel (2.2.10-ac4 or 2.2.5) I have 8+ Mo/s reading, which
    can be explained (I guess) due to heads movements and seek times.

    So, it seems that SMP has big trouble when parrallelizing readings (maybe
    a problem with SCSI, I do not know, since I have no IDE on the SMP box).

    Thierry Danis
    Poste : 53 53

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