Date: Mon, 7 Aug 2006 19:41:59 -0700
From: Andrew Morton <akpm@osdl.org>
To: Andi Kleen <ak@suse.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
       "Randy.Dunlap" <rdunlap@xenotime.net>,
       "Protasevich, Natalie" <Natalie.Protasevich@unisys.com>,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86_64: Make NR_IRQS configurable in Kconfig
Message-Id: <20060807194159.f7c741b5.akpm@osdl.org>
In-Reply-To: <200608080417.59462.ak@suse.de>
References: <m1irl4ftya.fsf@ebiederm.dsl.xmission.com>
	<m1slk89ozd.fsf@ebiederm.dsl.xmission.com>
	<20060807165512.dabefb63.akpm@osdl.org>
	<200608080417.59462.ak@suse.de>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1173
Lines: 31

On Tue, 8 Aug 2006 04:17:59 +0200
Andi Kleen <ak@suse.de> wrote:

> 
> > 
> > And it's a pretty nasty one because it can get people into the situation
> > where the kernel worked fine for those who released it, but users who
> > happen to load more modules (or the right combination of them) will
> > experience per-cpu memory exhaustion.
> 
> Yes, and a high value will waste a lot of memory for normal users.
>  
> > So shouldn't we being scaling the per-cpu memory as well?
> 
> If we move it into vmalloc space it would be easy to extend at runtime - just the
> virtual address space would need to be prereserved, but then more pages
> could be mapped. Maybe we should just do that instead of continuing to kludge around?

Sounds sane.

otoh, we need something for 2.6.19.

> Drawback would be some more TLB misses.

yup.  On some (important) architectures - I'm not sure which architectures
do the bigpage-for-kernel trick.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/