X not swapping - Setup

This is a discussion on X not swapping - Setup ; For a long time (over a year) I didn't have any swap space on my system. It was a testing installation (of Debian on a dual-boot fakeraid stripe set) and it didn't get used much. Finally the Debian installer got ...

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Thread: X not swapping

  1. X not swapping

    For a long time (over a year) I didn't have any swap space on my system. It
    was a testing installation (of Debian on a dual-boot fakeraid stripe set)
    and it didn't get used much. Finally the Debian installer got to grips with
    dmraid and I started using the system properly. It was a year before I
    emptied one of the Windows partitions and created a swap partition. The
    swap space (2GB) is all present and correct:

    chrisc@tony:~$ cat /proc/meminfo
    MemTotal: 1036372 kB
    MemFree: 653744 kB
    Buffers: 15548 kB
    Cached: 156616 kB
    SwapCached: 0 kB
    Active: 192116 kB
    Inactive: 97708 kB
    HighTotal: 131008 kB
    HighFree: 244 kB
    LowTotal: 905364 kB
    LowFree: 653500 kB
    SwapTotal: 1959888 kB
    SwapFree: 1959888 kB
    Dirty: 8 kB
    Writeback: 0 kB
    AnonPages: 117660 kB
    Mapped: 71328 kB
    Slab: 14732 kB
    SReclaimable: 7928 kB
    SUnreclaim: 6804 kB
    PageTables: 2868 kB
    NFS_Unstable: 0 kB
    Bounce: 0 kB
    CommitLimit: 2478072 kB
    Committed_AS: 627692 kB
    VmallocTotal: 114680 kB
    VmallocUsed: 8344 kB
    VmallocChunk: 105460 kB

    chrisc@tony:~$ cat /proc/swaps
    Filename Type Size Used
    Priority
    /dev/mapper/sil_aebgdidebbaj7 partition 1959888 0 -1


    The problem is that it never gets used. The system slows right down as I do
    more stuff, CPU usage goes up to 99% with increasing frequency, but nothing
    is ever swapped out.

    I'm using KDE on up-to-date Debian Lenny. I'm not an expert with X, and I
    thought swapping was a kernel-level activity, but is there something else I
    need to reconfigure?

    Apologies if this sounds stupid. Could the slowdowns be totally unrelated to
    swapping? I'm using the 'radeon' video driver on a bog-standard 9600PRO
    video card (Xorg.0.log says "(--) Chipset ATI Radeon 9600 AP (AGP) found").

    Thanks in advance for any help - the slowdowns are really annoying!

    CC

  2. Re: X not swapping

    Magnate writes:

    >For a long time (over a year) I didn't have any swap space on my system. It
    >was a testing installation (of Debian on a dual-boot fakeraid stripe set)
    >and it didn't get used much. Finally the Debian installer got to grips with
    >dmraid and I started using the system properly. It was a year before I
    >emptied one of the Windows partitions and created a swap partition. The
    >swap space (2GB) is all present and correct:


    .....

    >The problem is that it never gets used. The system slows right down as I do
    >more stuff, CPU usage goes up to 99% with increasing frequency, but nothing
    >is ever swapped out.


    swap is only used if the system needs more memory. You do not need more
    memory. If you did, and you did not use swap your system would crash. The
    system running slowly has absolutely nothing to do with swap (In fact if it
    did yuse swap it would go vry slowly).



    >I'm using KDE on up-to-date Debian Lenny. I'm not an expert with X, and I
    >thought swapping was a kernel-level activity, but is there something else I
    >need to reconfigure?


    >Apologies if this sounds stupid. Could the slowdowns be totally unrelated to
    >swapping? I'm using the 'radeon' video driver on a bog-standard 9600PRO
    >video card (Xorg.0.log says "(--) Chipset ATI Radeon 9600 AP (AGP) found").


    No, the slowdowns are not related to not swapping. You need to look
    elsewhere

    Run top, and see which program is using up all the CPU time.
    Programs could also run slowly if your hard drive is beginning to fail.




    >Thanks in advance for any help - the slowdowns are really annoying!


    >CC


  3. Re: X not swapping

    Unruh wrote:
    > swap is only used if the system needs more memory. You do not need more
    > memory. If you did, and you did not use swap your system would crash.


    Not quite true.
    The system's kernel would begin to initiate an out of memory policy to
    return to a stable state. This usually takes the form of the OOM Killer
    which picks processes out of the process table and kills them, freeing the
    RAM they took up.

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    | Andrew Halliwell BSc | |
    | in | "I think so brain, but this time, you control |
    | Computer Science | the Encounter suit, and I'll do the voice..." |

  4. Re: X not swapping

    Unruh wrote:
    > Magnate writes:
    >
    >> For a long time (over a year) I didn't have any swap space on my system. It
    >> was a testing installation (of Debian on a dual-boot fakeraid stripe set)
    >> and it didn't get used much. Finally the Debian installer got to grips with
    >> dmraid and I started using the system properly. It was a year before I
    >> emptied one of the Windows partitions and created a swap partition. The
    >> swap space (2GB) is all present and correct:

    >
    > ....
    >
    >> The problem is that it never gets used. The system slows right down as I do
    >> more stuff, CPU usage goes up to 99% with increasing frequency, but nothing
    >> is ever swapped out.

    >
    > swap is only used if the system needs more memory. You do not need more
    > memory. If you did, and you did not use swap your system would crash. The
    > system running slowly has absolutely nothing to do with swap (In fact if it
    > did use swap it would go very slowly).
    >
    >> I'm using KDE on up-to-date Debian Lenny. I'm not an expert with X, and I
    >> thought swapping was a kernel-level activity, but is there something else I
    >> need to reconfigure?

    >
    >> Apologies if this sounds stupid. Could the slowdowns be totally unrelated to
    >> swapping? I'm using the 'radeon' video driver on a bog-standard 9600PRO
    >> video card (Xorg.0.log says "(--) Chipset ATI Radeon 9600 AP (AGP) found").

    >
    > No, the slowdowns are not related to not swapping. You need to look
    > elsewhere


    Ok, fair enough.

    > Run top, and see which program is using up all the CPU time.


    Er, that would be Xorg, by a long way. Nothing else ever gets above a
    few percent for more than a few seconds, whereas Xorg stays at 99% for
    30-40 seconds at a time, frequently.

    Googling for "Xorg 99% CPU" returns hits about an Xrender bug in
    Nvidia's glx driver, but nothing about the radeon driver. The symptoms
    sound the same though (it's only graphical apps that cause the slowdown,
    esp. browsers, never consoles).

    Perhaps it is simply the old chestnut of poor video performance under X.
    The 'vesa' driver is ok for 2D but crap for 3D. The 'radeon' driver
    seems ok for 3D but perhaps is the culprit here. I'd be interested if
    anyone else uses radeon and has had the same problem.

    Googling for "Xorg radeon driver" returns lots of info but no references
    to this 99% CPU problem at all.

    Finally I found this page

    http://tsdgeos.blogspot.com/2007/10/...e-drivers.html

    which seems to indicate that it is just a performance issue with the
    radeon driver and I have to be patient while the driver is improved. Ho hum.

    > Programs could also run slowly if your hard drive is beginning to fail.


    But this would not manifest itself in 99% CPU usage, surely?

    CC

  5. Re: X not swapping

    On Thu, 31 Jul 2008 02:31:50 -0400, Magnate wrote:

    > Googling for "Xorg radeon driver" returns lots of info but no references
    > to this 99% CPU problem at all.


    Which radeon card? You may be better off using the ati driver, instead
    of the raedon driver. I'm using a radeon 9200SE with
    x11-driver-video-ati-6.8.191-1mdv2008.1.i586.rpm on Mandriva 2008.1

    In /etc/X11/xorg.conf I have ...
    Section "Device"
    Identifier "device1"
    VendorName "ATI Technologies Inc"
    BoardName "ATI Radeon 9250 and earlier"
    Driver "ati"
    Option "DPMS"
    Option "AccelMethod" "XAA"
    Option "XaaNoOffscreenPixmaps" "1"
    Option "AGPMode" "8"
    Option "ColorTiling" "on"
    EndSection

    Regards, Dave Hodgins

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  6. Re: X not swapping

    "David W. Hodgins" wrote in message
    newsp.ue55wcwwa3w0dxdave@hodgins.homeip.net...
    > On Thu, 31 Jul 2008 02:31:50 -0400, Magnate wrote:
    >
    >> Googling for "Xorg radeon driver" returns lots of info but no references
    >> to this 99% CPU problem at all.

    >
    > Which radeon card? You may be better off using the ati driver, instead
    > of the raedon driver. I'm using a radeon 9200SE with
    > x11-driver-video-ati-6.8.191-1mdv2008.1.i586.rpm on Mandriva 2008.1


    Hmm. I'm using a 9600PRO, which is an r300 card (rv350 to be precise), so
    'radeon' should be the optimal driver.

    According to Debian, xserver-xorg-video-ati is merely a wrapping for
    choosing the correct ATi driver, so it would choose radeon for me anyway
    (the alternatives being only mach64 or r128).

    > In /etc/X11/xorg.conf I have ...
    > Section "Device"
    > Identifier "device1"
    > VendorName "ATI Technologies Inc"
    > BoardName "ATI Radeon 9250 and earlier"
    > Driver "ati"
    > Option "DPMS"
    > Option "AccelMethod" "XAA"
    > Option "XaaNoOffscreenPixmaps" "1"
    > Option "AGPMode" "8"
    > Option "ColorTiling" "on"
    > EndSection


    Thanks. I've found a few guides for this, and I think the problem is with
    AGPFastWrite. If I set it to "on", X does not start at all (there are plenty
    of warnings about this - it seems to be a very risky option).

    Hopefully future development of the open source r300 driver will improve
    rendering acceleration, which may solve this problem.

    CC



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