hwpmc dealing with sparse cpu systems.

[John Baldwin]

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.
 
> -Alfred
> 
> ----- 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
> 
> Thanks,
> Sunil
> 
> 
> 
> ----- End forwarded message -----
> 
> -- 
> - Alfred Perlstein
> 



-- 
John Baldwin