Re: 2.6.18 is problematic in VMware

[Mark Lord <lkml@rtr.ca>]

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.

Cheers
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