Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750829AbWHHFKI (ORCPT ); Tue, 8 Aug 2006 01:10:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750835AbWHHFKI (ORCPT ); Tue, 8 Aug 2006 01:10:08 -0400 Received: from ozlabs.org ([203.10.76.45]:8655 "EHLO ozlabs.org") by vger.kernel.org with ESMTP id S1750829AbWHHFKG (ORCPT ); Tue, 8 Aug 2006 01:10:06 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <17624.7310.856480.704542@cargo.ozlabs.ibm.com> Date: Tue, 8 Aug 2006 15:09:34 +1000 From: Paul Mackerras To: Andrew Morton Cc: Andi Kleen , "Eric W. Biederman" , "Randy.Dunlap" , "Protasevich, Natalie" , linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86_64: Make NR_IRQS configurable in Kconfig In-Reply-To: <20060807194159.f7c741b5.akpm@osdl.org> References: <20060807165512.dabefb63.akpm@osdl.org> <200608080417.59462.ak@suse.de> <20060807194159.f7c741b5.akpm@osdl.org> X-Mailer: VM 7.19 under Emacs 21.4.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 755 Lines: 19 Andrew Morton writes: > > Drawback would be some more TLB misses. > > yup. On some (important) architectures - I'm not sure which architectures > do the bigpage-for-kernel trick. I looked at optimizing the per-cpu data accessors on PowerPC and only ever saw fractions of a percent change in overall performance, which says to me that we don't actually use per-cpu data all that much. So unless you make per-cpu data really really slow, I doubt that we'll see any significant performance difference. Paul. - 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/