From: Andrew Morton <akpm@osdl.org>
To: Paul Jackson <pj@sgi.com>
Cc: rajesh.shah@intel.com, mingo@elte.hu, linux-kernel@vger.kernel.org
Subject: Re: [patch 1/1] export cpu_online_map
Date: Thu, 27 Oct 2005 11:26:35 -0700 [thread overview]
Message-ID: <20051027112635.3d0a7199.akpm@osdl.org> (raw)
In-Reply-To: <20051027063859.20fcb9bb.pj@sgi.com>
Paul Jackson <pj@sgi.com> wrote:
>
> Andrew wrote:
> > Sweet, thanks. Perhaps we can remove cpu_online_map from UP builds soon -
> > it's really wrong to have it there.
>
> Eh ... my gut reaction is different. Even uni-processors have
> online cpus - just not very many of them (and hot unplugging one
> of them is frowned on).
That's daft. A uniprocessor machine has one and only one CPU and it's
always online! An online_map is only needed for MP.
Now conceptually, yes, we should be able to query and perhaps set the
onlineness of a CPU. But that doesn't mean that we should have storage
which idiotically remembers something which was known at compile time.
> Why make special cases when it serves no purpose?
Ths presence of cpu_online_map in UP builds _is_ a special case. The
kernel's overall approach to such things is to optimise them away at
compile time for !SMP builds.
next prev parent reply other threads:[~2005-10-27 18:27 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-10-26 4:20 akpm
2005-10-27 3:50 ` Paul Jackson
2005-10-27 4:08 ` Andrew Morton
2005-10-27 8:55 ` Paul Jackson
2005-10-27 9:35 ` Andrew Morton
2005-10-27 13:38 ` Paul Jackson
2005-10-27 18:26 ` Andrew Morton [this message]
2005-10-27 19:08 ` Paul Jackson
2005-10-27 13:49 ` Paul Jackson
2005-10-27 10:48 ` Diego Calleja
2005-10-27 14:06 ` Paul Jackson
2005-10-28 2:49 ` Herbert Xu
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