what's the timer resolution in Linux - Suse

This is a discussion on what's the timer resolution in Linux - Suse ; Hi all, I am just wondering what's the timer (any timer, I mean) resolution under Linux. I got a vague idea that the timer resolution under Linux is high than BSD, but what's the exactly value of it? Thanks in ...

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  1. what's the timer resolution in Linux

    Hi all,

    I am just wondering what's the timer (any timer, I mean) resolution under
    Linux. I got a vague idea that the timer resolution under Linux is high than
    BSD, but what's the exactly value of it?

    Thanks in advance.

    Regards,
    Xiaochuan



  2. Re: what's the timer resolution in Linux

    Xiaochuan Shen wrote:

    > Hi all,
    >
    > I am just wondering what's the timer (any timer, I mean) resolution under
    > Linux. I got a vague idea that the timer resolution under Linux is high
    > than BSD, but what's the exactly value of it?
    >
    > Thanks in advance.
    >
    > Regards,
    > Xiaochuan


    This may help:

    http://www.freescale.com/files/soft_...WLNXRTOSWP.pdf

  3. Re: what's the timer resolution in Linux

    On Nov 27, 4:54 pm, "Xiaochuan Shen" wrote:
    > Hi all,
    >
    > I am just wondering what's the timer (any timer, I mean) resolution under
    > Linux. I got a vague idea that the timer resolution under Linux is high than
    > BSD, but what's the exactly value of it?
    >
    > Thanks in advance.
    >
    > Regards,
    > Xiaochuan


    The default kernel in opensuse has the value 250 HZ.
    I know that all newer kernels allow to choose between 100, 250, 300,
    1000

    just find the kernel config file to look up your HZ value:
    .config inside the kernel build directory, or (as in my opensuse
    installation):
    /boot/config-[someKernelVersion]

    search inside the config file for CONFIG_HZ_

  4. Re: what's the timer resolution in Linux

    On Tue, 27 Nov 2007 11:17:21 -0800, linuxadmin wrote:

    > The default kernel in opensuse has the value 250 HZ.
    > I know that all newer kernels allow to choose between 100, 250, 300,
    > 1000


    Or to have the kernel run tickless.

  5. Re: what's the timer resolution in Linux

    linuxadmin@yandex.ru in
    <321338d7-2628-46f4-b2c3-47bcc27feb5b@e25g2000prg.googlegroups.com> :


    > just find the kernel config file to look up your HZ value:
    > .config inside the kernel build directory, or (as in my opensuse
    > installation):
    > /boot/config-[someKernelVersion]
    >
    > search inside the config file for CONFIG_HZ


    peter@dharma:~:0>zgrep CONFIG_HZ /proc/config.gz

    # CONFIG_HZ_100 is not set
    CONFIG_HZ_250=y
    # CONFIG_HZ_300 is not set
    # CONFIG_HZ_1000 is not set
    CONFIG_HZ=250

    P.


    --
    mailtoeter@dharma.dyn-o-saur.com

  6. Re: what's the timer resolution in Linux

    linuxadmin@yandex.ru in
    <321338d7-2628-46f4-b2c3-47bcc27feb5b@e25g2000prg.googlegroups.com> :


    > The default kernel in opensuse has the value 250 HZ.
    > I know that all newer kernels allow to choose between 100, 250, 300,
    > 1000


    But i'm wandering what kind off difference it should make.
    What kind of response could we expect if the resolution would be set to 100
    or 1000? What does this CONFIG_HZ/resolution value do to a machine?

    Kind Regards,

    Peter

    --
    mailtoeter@dharma.dyn-o-saur.com

  7. Re: what's the timer resolution in Linux

    Peter Terpstra wrote:
    > linuxadmin@yandex.ru in
    > <321338d7-2628-46f4-b2c3-47bcc27feb5b@e25g2000prg.googlegroups.com> :
    >
    >
    >> The default kernel in opensuse has the value 250 HZ.
    >> I know that all newer kernels allow to choose between 100, 250, 300,
    >> 1000

    >
    > But i'm wandering what kind off difference it should make.
    > What kind of response could we expect if the resolution would be set to 100
    > or 1000? What does this CONFIG_HZ/resolution value do to a machine?


    Higher values provide finer-grained time measurement to applications.
    3D games benefit from this, since they have times that fire off multiple
    times even before the monitor finished drawing a single frame.
    Multimedia authoring applications are said to also benefit from this
    (can someone explain why though?)

    For a non-gaming PC, even 100Hz is good enough. On 32-bit systems it
    doesn't matter much though, since the kernel is "tickless" by default
    (that is the interrupt timer is effectively disabled when not needed).
    On x86_64 tickless doesn't work (yet), so it matters a bit. The general
    rule is, if you're playing modern 3D games, 1000Hz is better. If not,
    choose 250 (or even 100 to save a bit of battery life on laptops).

  8. Re: what's the timer resolution in Linux

    Peter Terpstra writes:

    >linuxadmin@yandex.ru in
    ><321338d7-2628-46f4-b2c3-47bcc27feb5b@e25g2000prg.googlegroups.com> :



    >> The default kernel in opensuse has the value 250 HZ.
    >> I know that all newer kernels allow to choose between 100, 250, 300,
    >> 1000


    >But i'm wandering what kind off difference it should make.
    >What kind of response could we expect if the resolution would be set to 100
    >or 1000? What does this CONFIG_HZ/resolution value do to a machine?


    That is not the timer resolution, since the timing routines also use the
    cpu ticks to interpolate between the timer interrupt ticks. The timing
    resolution under Linux is about 1usec ( one millionth of a second), not the
    10 or 4 of 2 or 1 milli sec that the above would indicate.

    >Kind Regards,


    >Peter


    >--
    >mailtoeter@dharma.dyn-o-saur.com


  9. Re: what's the timer resolution in Linux

    Nikos Chantziaras in :

    > Higher values provide finer-grained time measurement to applications.
    > 3D games benefit from this, since they have times that fire off multiple
    > times even before the monitor finished drawing a single frame.
    > Multimedia authoring applications are said to also benefit from this
    > (can someone explain why though?)
    >
    > For a non-gaming PC, even 100Hz is good enough. *On 32-bit systems it
    > doesn't matter much though, since the kernel is "tickless" by default
    > (that is the interrupt timer is effectively disabled when not needed).
    > On x86_64 tickless doesn't work (yet), so it matters a bit. *The general
    > rule is, if you're playing modern 3D games, 1000Hz is better. *If not,
    > choose 250 (or even 100 to save a bit of battery life on laptops).


    Ah thanks for this info, i get the idea to compile different kernels to
    experiment with this.

    P.

    --
    mailtoeter@dharma.dyn-o-saur.com

  10. Re: what's the timer resolution in Linux

    Unruh in :

    > That is not the timer resolution, since the timing routines also use the
    > cpu ticks to interpolate between the timer interrupt ticks. The timing
    > resolution under Linux is about 1usec ( one millionth of a second), not
    > the 10 or 4 of 2 or 1 milli sec that the above would indicate.


    I believe you :-)

    P.

    --
    mailtoeter@dharma.dyn-o-saur.com

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