From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 7 May 2008 18:57:05 -0700 (PDT) From: Linus Torvalds Subject: Re: [PATCH 08 of 11] anon-vma-rwsem In-Reply-To: <20080508015249.GT8276@duo.random> Message-ID: References: <20080507222205.GC8276@duo.random> <20080507153103.237ea5b6.akpm@linux-foundation.org> <20080507224406.GI8276@duo.random> <20080507155914.d7790069.akpm@linux-foundation.org> <20080508015249.GT8276@duo.random> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Andrea Arcangeli Cc: Christoph Lameter , Andrew Morton , steiner@sgi.com, holt@sgi.com, npiggin@suse.de, a.p.zijlstra@chello.nl, kvm-devel@lists.sourceforge.net, kanojsarcar@yahoo.com, rdreier@cisco.com, swise@opengridcomputing.com, linux-kernel@vger.kernel.org, avi@qumranet.com, linux-mm@kvack.org, general@lists.openfabrics.org, hugh@veritas.com, rusty@rustcorp.com.au, aliguori@us.ibm.com, chrisw@redhat.com, marcelo@kvack.org, dada1@cosmosbay.com, paulmck@us.ibm.com List-ID: On Thu, 8 May 2008, Andrea Arcangeli wrote: > > So because the bitflag can't prevent taking the same lock twice on two > different vmas in the same mm, we still can't remove the sorting Andrea. Take five minutes. Take a deep breadth. And *think* about actually reading what I wrote. The bitflag *can* prevent taking the same lock twice. It just needs to be in the right place. Let me quote it for you: > So the flag wouldn't be one of the VM_xyzzy flags, and would require > adding a new field to "struct anon_vma()" IOW, just make it be in that anon_vma (and the address_space). No sorting required. > I think it's more interesting to put a cap on the number of vmas to > min(1024,max_map_count). The sort time on an 8k array runs in constant > time. Shut up already. It's not constant time just because you can cap the overhead. We're not in a university, and we care about performance, not your made-up big-O notation. Linus -- 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