From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <439D2135.4050804@yahoo.com.au> Date: Mon, 12 Dec 2005 18:05:25 +1100 From: Nick Piggin MIME-Version: 1.0 Subject: Re: [RFC 1/6] Framework References: <20051210005440.3887.34478.sendpatchset@schroedinger.engr.sgi.com> <20051210005445.3887.94119.sendpatchset@schroedinger.engr.sgi.com> <439CF2A2.60105@yahoo.com.au> <20051212035631.GX11190@wotan.suse.de> <439CF93D.5090207@yahoo.com.au> <20051212042142.GZ11190@wotan.suse.de> <439CFC67.4030107@yahoo.com.au> <20051212045146.GA11190@wotan.suse.de> In-Reply-To: <20051212045146.GA11190@wotan.suse.de> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andi Kleen Cc: Christoph Lameter , linux-kernel@vger.kernel.org, Hugh Dickins , linux-mm@kvack.org, Marcelo Tosatti List-ID: Andi Kleen wrote: >>Then you can't use __local_xxx, and so many architectures will use >>atomic instructions (the ones who don't are the ones with tripled >>cacheline footprint of this structure). > > > They are wrong then. atomic instructions is the wrong implementation > and they would be better off with asm-generic. > Yes I mean atomic and per-cpu. Same as asm-generic. > If anything they should use per_cpu counters for interrupts and > use seq locks. How would seqlocks help? > Or just turn off the interrupts for a short time > in the low level code. > This is exactly what mod_page_state does, which is what my patches eliminate. For a small but significant performance improvement. > >>Sure i386 and x86-64 are happy, but this would probably slow down >>most other architectures. > > > I think it is better to fix the other architectures then - if they > are really using a full scale bus lock for this they're just wrong. > > I don't think it is a good idea to do a large change in generic > code just for dumb low level code. > It is not a large change at all, just some shuffling of mod_page_state and friends to go under pre-existing interrupts-off sections. -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org