linux-kernel - Re: 2.6.18 is problematic in VMware

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Date:	Tue, 31 Oct 2006 08:59:22 +0100 (MET)
From:	Jan Engelhardt <jengelh@...ux01.gwdg.de>
To:	Zachary Amsden <zach@...are.com>
cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: 2.6.18 is problematic in VMware


>> 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


	-`J'
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