From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <43BF3355.5060606@yahoo.com.au> Date: Sat, 07 Jan 2006 14:19:49 +1100 From: Nick Piggin MIME-Version: 1.0 Subject: Re: [PATCH] use local_t for page statistics References: <20060106215332.GH8979@kvack.org> <20060106163313.38c08e37.akpm@osdl.org> <43BF2D03.2030908@yahoo.com.au> <200601070401.47618.ak@suse.de> In-Reply-To: <200601070401.47618.ak@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: Andrew Morton , Benjamin LaHaise , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: Andi Kleen wrote: > On Saturday 07 January 2006 03:52, Nick Piggin wrote: > > >>No. On many load/store architectures there is no good way to do local_t, >>so something like ppc32 or ia64 just uses all atomic operations for > > > well, they're just broken and need to be fixed to not do that. > How? > Also I bet with some tricks a seqlock like setup could be made to work. > I asked you how before. If you can come up with a way then it indeed might be a good solution... The problem I see with seqlock is that it is only fast in the read path. That path is not the issue here. > >>local_t, and ppc64 uses 3 counters per-cpu thus tripling the cache >>footprint. > > > and ppc64 has big caches so this also shouldn't be a problem. > Well it is even less of a problem for them now, by about 1/3. Performance-wise there is really no benefit for even i386 or x86-64 to move to local_t now either so I don't see what the fuss is about. -- 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