From: Nathan Lynch <ntl@pobox•com>
To: Tony Breeds <tony@bakeyournoodle•com>
Cc: linuxppc-dev@ozlabs•org
Subject: Re: [PATCH] kill useless SMT code in prom_hold_cpus
Date: Mon, 14 Jul 2008 23:55:51 -0500 [thread overview]
Message-ID: <20080715045551.GV9594@localdomain> (raw)
In-Reply-To: <20080715022202.GD20457@bakeyournoodle.com>
Tony Breeds wrote:
> On Tue, Jul 08, 2008 at 05:36:31PM -0500, Nathan Lynch wrote:
>
> > - prom_printf("%x : starting cpu hw idx %x... ", cpuid, reg);
> > + prom_printf("starting cpu hw idx %x... ", reg);
>
> If we remove this, where else can we see the mapping of hardware IDs
> to logical cpu IDs? This is useful on POWER4 (at least where they can be
> different).
sysfs. (e.g. /sys/devices/system/cpu/cpu0/physical_id)
> > - if (cpuid > NR_CPUS)
> > - prom_printf("WARNING: maximum CPUs (" __stringify(NR_CPUS)
> > - ") exceeded: ignoring extras\n");
> > -
>
> I think this printf() is valuable, if your boot a 128 thread machine on
> a kernel with NR_CPUS=64, this is the only messaage you get to indicate
> that you're wasting 64 threads, and how to resolve it.
The proper place for such a message is in the kernel's smp bringup
code later on, and/or the code that initializes the various cpu maps.
The prom_init code should not really be concerned with the kernel's
NR_CPUS configuration or mapping of logical to physical ids.
next prev parent reply other threads:[~2008-07-15 4:56 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-08 22:36 [PATCH] kill useless SMT code in prom_hold_cpus Nathan Lynch
2008-07-15 2:05 ` Benjamin Herrenschmidt
2008-07-15 2:24 ` Nathan Lynch
2008-07-15 4:53 ` Benjamin Herrenschmidt
2008-07-15 2:22 ` Tony Breeds
2008-07-15 4:55 ` Nathan Lynch [this message]
2008-07-15 4:59 ` Tony Breeds
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