hwpmc dealing with sparse cpu systems.
jhb at freebsd.org
Fri Oct 12 13:38:15 PDT 2007
On Friday 12 October 2007 04:00:06 pm Alfred Perlstein wrote:
> One of the engineers here seems to have found a bug in the
> hwpmc_mod.c module. The problem we have is that cpuids can
> be greater than mp_ncpus due to sparseness.
> Does the fix here make sense? (replace mp_ncpus with MAXCPU)
> I would like to commit it.
Actually, mp_maxid is what you should use. It is guaranteed that all CPU IDs
are <= mp_maxid.
> ----- Forwarded message from Alfred Perlstein <perlstein at juniper.net> -----
> From: "Sunil Mudunuri"
> Subject: Re: hwpmc on mpsdk.
> Date: Thu, 11 Oct 2007 18:11:27 -0700
> Message-ID: <470EC9BF.5070607 at juniper.net>
> User-Agent: Mozilla Thunderbird 1.0 (X11/20041206)
> Looking at the code in hwpmc_mod.c, I feel that
> the mp_ncpus (global) is wrongly used in this module.
> While mp_ncpus is the count of active cpus in the system,
> this is being used to range check a cpu id(active/inactive) which can be
> greater than mp_ncpus.
> The code works fine in systems which has all the cpu's active eg.
> SPU(australia), but is causing crashes
> in mpsdk where we have the active cpus interleaved with idle cpu's.
> I replaced mp_ncpus with MAXCPU in almost all the places and it works fine.
> So this should be fixed in the FreeBSD proper, I guess.
> Alfred/Girish, can you push this to be fixed in FreeBSD
> ----- End forwarded message -----
> - Alfred Perlstein
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