lkml.org 
[lkml]   [2001]   [May]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: [patch]: ide dma timeout retry in pio
    Date

    ----- Original Message -----
    From: "Alan Cox" <alan@lxorguk.ukuu.org.uk>
    To: "Mark Hahn" <hahn@coffee.psychology.mcmaster.ca>
    Cc: "Jens Axboe" <axboe@suse.de>; <andre@linux-ide.org>;
    <alan@lxorguk.ukuu.org.uk>; <linux-kernel@vger.kernel.org>
    Sent: Monday, May 28, 2001 5:12 PM
    Subject: Re: [patch]: ide dma timeout retry in pio


    > > really? do we know the nature of the DMA engine problem well
    enough?
    >
    > I can categorise some of them:
    >
    > 1. Hardware that just doesnt support it.
    > 2. Timeouts that are false positives caused by disks having problems
    > and being very slow to recover
    > 3. Bad cabling
    > 4. Stalls caused by heavy PCI traffic
    >
    > > is there a reason to believe that it'll work better "later"?
    >
    > #1 will go fail, fail, fail -> PIO now (or should do Im about to try
    it)
    > #2 and #4 will be transient
    > #3 could go either way


    Where does the "'DMA Timeout -> disable DMA' then lose all
    responsiveness when I issue 'hdparm -d1' while it tries and fails to
    re-enable DMA" fit in? The disk will happily run for several days in
    UDMA33 and then at some point it craps out with a DMA timeout which
    results 1) DMA being turned off and 2) all attempts to re-enable DMA
    failing?

    And what's up with this:

    [root@MoveAlong james]# hdparm /dev/hda

    /dev/hda:
    multcount = 0 (off)
    I/O support = 1 (32-bit)
    unmaskirq = 1 (on)
    using_dma = 1 (on)
    keepsettings = 1 (on)
    nowerr = 0 (off)
    readonly = 0 (off)
    readahead = 8 (on)
    geometry = 19590/16/63, sectors = 19746720, start = 0
    [root@MoveAlong james]# hdparm -tT /dev/hda

    /dev/hda:
    Timing buffer-cache reads: 128 MB in 6.98 seconds = 18.34 MB/sec
    Timing buffered disk reads: 64 MB in 5.77 seconds = 11.09 MB/sec
    Hmm.. suspicious results: probably not enough free memory for a proper
    test.
    [root@MoveAlong james]# free
    total used free shared buffers
    cached
    Mem: 126800 123460 3340 0 67284
    41572
    -/+ buffers/cache: 14604 112196
    Swap: 394624 32816 361808

    I used to get ~33MB/sec on buffer-cache and ~10MB/sec on buffered disk
    reads in 2.2...

    --JT

    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 12:54    [W:0.026 / U:59.212 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site