Excessive fdisk(8) delays

From: Peter Jeremy (PeterJeremy_at_optushome.com.au)
Date: 08/20/04

  • Next message: Warren Liddell: "installworld Failure" 
    Date: Sat, 21 Aug 2004 06:50:39 +1000
To: freebsd-stable@freebsd.org

    I haven't noticed this before and don't recall it being mentioned before...

    I just did an 'fdisk ad1' whilst ad0 was being hammered and the fdisk
    spat out all the expected information then hung (in "atalck") for
    about 4½ minutes before exiting. This was repeatable and very
    disconcerting the first time.

    Background: The system is an AMD Athlon-XP running -STABLE from the
    beginning of August with two 100GB WD drives running at UDMA100
    attached to channel 0 of a VIA VT8233A. The "hammering" was a dd of
    the raw disk, a "find /" and a "cvs update" (systat -v report 100%
    utilisation of ad0).

    A quick check of the code shows "atalck" is used within ATA_SLEEPLOCK_CH
    to wait for the channel to be come idle and this macro is used fairly
    extensively within the ata code. Having I/O requests queued for over
    4 minutes seems excessive - how difficult would it be for the ata code
    to better round-robin requests? (Possibly via a wakeup at the end of
    ata_start()). 

    -- 
Peter Jeremy
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  • Next message: Warren Liddell: "installworld Failure"