Messages in this thread | | | Date | Tue, 31 Oct 2006 09:06:07 -0500 | From | Mark Lord <> | Subject | Re: 2.6.18 is problematic in VMware |
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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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