From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 18 Oct 2007 19:01:52 -0700 (PDT) From: Christoph Lameter Subject: Re: SLUB: Avoid atomic operation for slab_unlock In-Reply-To: <200710191156.43049.nickpiggin@yahoo.com.au> Message-ID: References: <200710190949.01019.nickpiggin@yahoo.com.au> <200710191156.43049.nickpiggin@yahoo.com.au> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Nick Piggin Cc: Linux Kernel Mailing List , akpm@linux-foundation.org, linux-mm@kvack.org List-ID: On Fri, 19 Oct 2007, Nick Piggin wrote: > > Yes that is what I attempted to do with the write barrier. To my knowledge > > there are no reads that could bleed out and I wanted to avoid a full fence > > instruction there. > > Oh, OK. Bit risky ;) You might be right, but anyway I think it > should be just as fast with the optimised bit_unlock on most > architectures. How expensive is the fence? An store with release semantics would be safer and okay for IA64. > Which reminds me, it would be interesting to test the ia64 > implementation I did. For the non-atomic unlock, I'm actually > doing an atomic operation there so that it can use the release > barrier rather than the mf. Maybe it's faster the other way around > though? Will be useful to test with something that isn't a trivial > loop, so the slub case would be a good benchmark. Lets avoid mf (too expensive) and just use a store with release semantics. Where can I find your patchset? I looked through lkml but did not see it. -- 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