Re: improving concurrency/performance

From: Jure Pečar (no email)
Date: Mon Nov 07 2005 - 16:31:42 EST

  • Next message: Jure Pečar: "Re: improving concurrency/performance"

    On Mon, 7 Nov 2005 12:41:03 -0500 (EST)
    "John Madden" <> wrote:

    > Perhaps it's worth repeating: With a single imapcopy process, the whole thing goes
    > along pretty quickly, but drops off significantly with a second process and comes
    > to basically a crawl with just 5 processes running concurrently. I gambled that I
    > could shorten my migration by running more than one at a time since one only seems
    > to raise the load on the box to 0.80. With 5, I'm only able to get it to around
    > 2.5 and only briefly as the throughput starts to drop off.

    That is a start. Try to strace -tt all of imapd processes running
    concurrently and examine in which syscalls most time is spent. I hope that
    would give you at least a lead ...

    For example, on my production system I see some suspicious long pauses at
    fcntl64(0x8, 0x7, 0xsomeaddr, 0xsomeotheraddr) calls ... lets dig what this
    is.

    -- 
    Jure Pečar
    http://jure.pecar.org/
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  • Next message: Jure Pečar: "Re: improving concurrency/performance"





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