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Date:      Fri, 27 May 2005 09:30:46 -0500
From:      Jacob S <stormspotter@6Texans.net>
To:        Dmitry Mityugov <dmitry.mityugov@gmail.com>
Cc:        freebsd-questions@freebsd.org
Subject:   Re: Problem with HT support in 5.4
Message-ID:  <20050527093046.748e33c1@jacob.6texans.net>
In-Reply-To: <b7052e1e05052707056d4faa4@mail.gmail.com>
References:  <20050527085445.38de5553@jacob.6texans.net> <b7052e1e05052707056d4faa4@mail.gmail.com>

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On Fri, 27 May 2005 18:05:48 +0400
Dmitry Mityugov <dmitry.mityugov@gmail.com> wrote:

> On 5/27/05, Jacob S wrote:
> > Hello list,
> > 
> > I upgraded a few 5.3 servers to 5.4 yesterday and everything seemed
> > to go well. After booting the new kernel, dmesg correctly showed 2
> > logical cpus (1 xeon with HT).
> > 
> > However, when I look at top's output, it always shows at least 50%
> > cpu idle time - even when the load is above 10. To confirm this, I
> > ran burnP6 from the cpuburn port - even with over a hundred apache
> > processes going, exim running and a few other things, top still
> > reported the cpu as 50% idle. The 'C' column in top, between 'State'
> > and 'Time' also shows everything as being run on cpu 0.
> > 
> > `ps ax | grep cpu` reports this:
> >  11  ??  RL     0:00.00 [idle: cpu1]
> >  12  ??  RL   931:45.24 [idle: cpu0]
> > 108  ??  DL     0:04.02 [schedcpu]
> > 
> > So it looks like smp support is enabled and it sees the HT enabled
> > processor, but it's not using the second logical cpu. Is there
> > something I missed in compiling the kernel, or is this a bug? I have
> > confirmed it on two 5.4 servers now.
> 
> Oh, wait, it is probably just the last HT security patch,
> ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-05:09.htt.asc.

hmm... So basically, SMP can be enabled, but it won't use HT even if it
sees a capable processor? 

Thanks,
Jacob



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