Re: [RT] read_tsc: ACK! TSC went backward! Unsynced TSCs?

From: Andi Kleen (ak_at_suse.de)
Date: 11/29/05

  • Next message: Salyzyn, Mark: "[2.6 patch] dpt_i2o fix for deadlock condition" 
    Date:	Tue, 29 Nov 2005 17:48:58 +0100
To: thockin@hockin.org

    On Tue, Nov 29, 2005 at 08:52:19AM -0800, thockin@hockin.org wrote:
    > On Tue, Nov 29, 2005 at 07:06:24AM -0700, Andi Kleen wrote:
    > > But I'm surprised you're saying 2.6.11 broke. At least 2.6.11 64bit should
    > > have always used HPET in this case. I only broke it around 2.6.13
    > > where I added an overeager optimization for single socket DC on my side based
    > > on a misunderstanding. Earlier and later kernels should have been ok.
    >
    > we didn't have HPET enabled in BIOS until recently. Turning that on made
    > all the TSC gettimeofday() crap disappear. Now to find and kill any
    > straggling users of rdtsc

    The newer kernels work around this too by using pmtimer when needed.
    Of course it's slow.

    Regarding straggling users of rdtsc - one way would be to optionally
    trap them and log them in the kernel. That would work in ring 3 at least.

    -Andi

    -
    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/

  • Next message: Salyzyn, Mark: "[2.6 patch] dpt_i2o fix for deadlock condition"

    Relevant Pages

    • Re: silent semantic changes with reiser4
      ... Or between Linux systems with different kernels that happen to implement ... just to be thrown out later because nobody used it. ... send the line "unsubscribe linux-kernel" in ...
      (Linux-Kernel)
    • Re: Bug in the sg driver
      ... | We traced the segfault to sg_ioctl trying to do something. ... | kernels where highmem is enabled. ... send the line "unsubscribe linux-kernel" in ...
      (Linux-Kernel)
    • [update] OOM issue with linux-2.6.14-rt6
      ... Both my embedded target boards have CF cards which are mounted ... with mkfs.minix I simply used that to create a minix filesystem on ... I'll let these kernels run over the weekend to see how they perform. ... send the line "unsubscribe linux-kernel" in ...
      (Linux-Kernel)
    • Restoring HDIO_GETGEO semantics for 2.6 (was: Re: [RFC] Restoring HDIO_GETGEO semantics)
      ... > it more clear that there is no attempt to return the BIOS geometry. ... 2.6 kernels made very visible that the widely used Parted, libparted, ... It's the restoration of the user space compatibility _and_ ... send the line "unsubscribe linux-kernel" in ...
      (Linux-Kernel)
    • Re: Very high load on P4 machines with 2.4.28
      ... The machines have normal load averages hovering not higher than ... > is climbing very fast and hovers around a value 3-4 times higher than with ... > the older kernels. ... send the line "unsubscribe linux-kernel" in ...
      (Linux-Kernel)