From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Fri, 17 Jun 2005 01:45:21 -0700 From: William Lee Irwin III Subject: Re: Global spinlock vs local bit spin locks Message-ID: <20050617084521.GG3913@holomorphy.com> References: <1118982092.5261.44.camel@npiggin-nld.site> <20050617044611.GF3913@holomorphy.com> <42B28B44.9090606@yahoo.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <42B28B44.9090606@yahoo.com.au> To: Nick Piggin Cc: "David S. Miller" , anton@samba.org, linux-arch@vger.kernel.org, Andrew Morton , Peter Keilty List-ID: William Lee Irwin III wrote: >> I'd feel far more comfortable with this if the lockbit resided in the >> page. Also, compare it to akpm's solution. On Fri, Jun 17, 2005 at 06:35:16PM +1000, Nick Piggin wrote: > akpm's solution is alright. They perform similarly on the workload in > question. Of course, the bitlock will scale quite a lot better if you > pushed it and will automatically be localised per device and have NUMA > locality, etc. > As far as page flags go - I agree but I didn't want to use one up. > This is very localised and I don't think it is particularly worse > than what was there before, so I think we can get away with it for > the moment. I'm ambivalent now I guess. I'm not wild about bh's in the first place, so infecting core code with new dependencies on them doesn't sound hot, though I still can't help cringing at using a bitflag in the first bh in the list to protect against concurrent teardown of the bh list, which relies on the setup/teardown patterns. Might as well stop bothering people about it, I guess. -- wli