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    SubjectRe: Swappiness vs. mmap() and interactive response
    On Tue, Apr 28, 2009 at 02:35:29PM +0900, KOSAKI Motohiro wrote:
    > (cc to linux-mm and Rik)
    >
    > > Hi,
    > >
    > > So, I just set up Ubuntu Jaunty (using Linux 2.6.28) on a quad core phenom box,
    > > and then I did the following (with XFS over LVM):
    > >
    > > mv /500gig/of/data/on/disk/one /disk/two
    > >
    > > This quickly caused the system to. grind.. to... a.... complete..... halt.
    > > Basically every UI operation, including the mouse in Xorg, started experiencing
    > > multiple second lag and delays. This made the system essentially unusable --
    > > for example, just flipping to the window where the "mv" command was running
    > > took 10 seconds on more than one occasion. Basically a "click and get coffee"
    > > interface.
    >
    > I have some question and request.
    >
    > 1. please post your /proc/meminfo
    > 2. Do above copy make tons swap-out? IOW your disk read much faster than write?
    > 3. cache limitation of memcgroup solve this problem?
    > 4. Which disk have your /bin and /usr/bin?

    I'll answer these out of order if you don't mind.

    2. Do above copy make tons swap-out? IOW your disk read much faster than write?

    The disks should be roughly similar. However:

    sda is the read disk, sdb is the write. Here's a few snippets from iostat -xm 10

    Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await svctm %util
    sda 67.70 0.00 373.10 0.20 48.47 0.00 265.90 1.94 5.21 2.10 78.32
    sdb 0.00 1889.60 0.00 139.80 0.00 52.52 769.34 35.01 250.45 5.17 72.28
    ---
    sda 5.30 0.00 483.80 0.30 60.65 0.00 256.59 1.59 3.28 1.65 79.72
    sdb 0.00 3632.70 0.00 171.10 0.00 61.10 731.39 117.09 709.66 5.84 100.00
    ---
    sda 51.20 0.00 478.10 1.00 65.79 0.01 281.27 2.48 5.18 1.96 93.72
    sdb 0.00 2104.60 0.00 174.80 0.00 62.84 736.28 108.50 613.64 5.72 100.00
    --
    sda 153.20 0.00 349.40 0.20 60.99 0.00 357.30 4.47 13.19 2.85 99.80
    sdb 0.00 1766.50 0.00 158.60 0.00 59.89 773.34 110.07 672.25 6.30 99.96

    This data seems to indicate the IO performance varies, but the reader is usually faster.

    4. Which disk have your /bin and /usr/bin?

    sda, the reader.

    3. cache limitation of memcgroup solve this problem?

    I was unable to get this to work -- do you have some documentation handy?

    1. please post your /proc/meminfo

    $ cat /proc/meminfo
    MemTotal: 3467668 kB
    MemFree: 20164 kB
    Buffers: 204 kB
    Cached: 2295232 kB
    SwapCached: 4012 kB
    Active: 639608 kB
    Inactive: 2620880 kB
    Active(anon): 608104 kB
    Inactive(anon): 360812 kB
    Active(file): 31504 kB
    Inactive(file): 2260068 kB
    Unevictable: 8 kB
    Mlocked: 8 kB
    SwapTotal: 4194296 kB
    SwapFree: 4186968 kB
    Dirty: 147280 kB
    Writeback: 8424 kB
    AnonPages: 961280 kB
    Mapped: 39016 kB
    Slab: 81904 kB
    SReclaimable: 59044 kB
    SUnreclaim: 22860 kB
    PageTables: 20548 kB
    NFS_Unstable: 0 kB
    Bounce: 0 kB
    WritebackTmp: 0 kB
    CommitLimit: 5928128 kB
    Committed_AS: 1770348 kB
    VmallocTotal: 34359738367 kB
    VmallocUsed: 281908 kB
    VmallocChunk: 34359449059 kB
    HugePages_Total: 0
    HugePages_Free: 0
    HugePages_Rsvd: 0
    HugePages_Surp: 0
    Hugepagesize: 2048 kB
    DirectMap4k: 44928 kB
    DirectMap2M: 3622912 kB



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