From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx198.postini.com [74.125.245.198]) by kanga.kvack.org (Postfix) with SMTP id 170DB6B0044 for ; Fri, 3 Aug 2012 20:05:37 -0400 (EDT) Received: by pbbrp2 with SMTP id rp2so2390159pbb.14 for ; Fri, 03 Aug 2012 17:05:36 -0700 (PDT) Date: Fri, 3 Aug 2012 17:05:31 -0700 From: Tejun Heo Subject: Re: [RFC v2 1/7] hashtable: introduce a small and naive hashtable Message-ID: <20120804000531.GP15477@google.com> References: <20120803171515.GH15477@google.com> <501C407D.9080900@gmail.com> <20120803213017.GK15477@google.com> <501C458E.7050000@gmail.com> <20120803214806.GM15477@google.com> <501C4E92.1070801@gmail.com> <20120803222339.GN15477@google.com> <20120803223634.GO15477@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Linus Torvalds Cc: Sasha Levin , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, paul.gortmaker@windriver.com, davem@davemloft.net, rostedt@goodmis.org, mingo@elte.hu, ebiederm@xmission.com, aarcange@redhat.com, ericvh@gmail.com, netdev@vger.kernel.org Hello, On Fri, Aug 03, 2012 at 04:47:47PM -0700, Linus Torvalds wrote: > On Fri, Aug 3, 2012 at 3:36 PM, Tejun Heo wrote: > > > > I suppose you mean unsized. I remember this working. Maybe I'm > > confusing it with zero-sized array. Hmm... gcc doesn't complain about > > the following. --std=c99 seems happy too. > > Ok, I'm surprised, but maybe it's supposed to work if you do it inside > another struct like that, exactly so that you can preallocate things.. Yeah, I think the rule is var array should be the last member of any given struct definition. Once a struct is defined, its alignment and size are fixed and it behaves like any other struct. > Or maybe it's just a gcc bug. I do think this all is way hackier than > Sasha's original simple code that didn't need these kinds of games, > and didn't need a size member at all. > > I really think all the extra complexity and overhead is just *bad*. > The first simple version was much nicer and likely generated better > code too. The size member could have performance impact in extreme cases. If we're looking for something simple & fast, maybe just pass in @size as argument and be done with it? Thanks. -- tejun -- 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