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    SubjectRe: 2.6.18 is problematic in VMware
    Jan Engelhardt wrote:
    >>> I have observed a strange slowdown with the 2.6.18 kernel in VMware. This
    >>> happened both with the SUSE flavor and with the FC6 installer CD (which I
    >>> am trying right now). In both cases, the kernel "takes its time" after the
    >>> following text strings:
    >>> * Checking if this processor honours the WP bit even in supervisor mode...
    >>> Ok.
    >>> * Checking 'hlt' instruction... OK.
    >>> What's with that?
    >> Thanks. It is perhaps the jiffies calibration taking a while because of the
    >> precise timing loop. Are you reasonably confident that it is a regression in
    >> performance over 2.6.17?
    > Yes. I am not exactly sure if it's something in jiffies calibration
    > (because of the 'WP bit/supervisor' thing too), so maybe I thought it
    > was the newly-introduced SMP alternatives. I gotta check that.
    >> The boot sequence is pretty complicated, and a lot of
    >> it is difficult / slow to virtualize, so it could just be alternate timing
    >> makes the boot output appear to stall, when in fact the raw time is still about
    >> the same. I will run some experiments.
    > Booting with 'time' shows that the virtual time increases as usual, i.e.
    > [ 9.00] checking if wp bit...
    > [15.00] next message here

    My experience with VMware on several recent processors (mostly P-M family)
    is that it crawls unless I force this first:
    echo 1 > /sys/module/processor/parameters/max_cstate

    So I use a wrapper script around VMware (workstation) to save max_cstate,
    set it to 1, and restore it again on exit.

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      Last update: 2006-10-31 15:09    [W:0.021 / U:20.600 seconds]
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