Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030189AbWHHQe5 (ORCPT ); Tue, 8 Aug 2006 12:34:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030190AbWHHQe4 (ORCPT ); Tue, 8 Aug 2006 12:34:56 -0400 Received: from smtp102.mail.mud.yahoo.com ([209.191.85.212]:28768 "HELO smtp102.mail.mud.yahoo.com") by vger.kernel.org with SMTP id S1030189AbWHHQe4 (ORCPT ); Tue, 8 Aug 2006 12:34:56 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:CC:Subject:References:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=VuqQwaHG/rMRmGvr4440G3O+GmCarJTKPybTWLJFiPaHMH0v8WEciTcgLYeCmOWHjKPV2e3Dj+DhiFcFN4SWNQBpp/X+SYUsTo5EWUWurBB6XAH77VHSyj0W7ZPCVBecZoP4R0mTXG5F2tChSu+CnCnjeDcafTzcrOmH+tu+jho= ; Message-ID: <44D8BD29.4010102@yahoo.com.au> Date: Wed, 09 Aug 2006 02:34:49 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051007 Debian/1.7.12-1 X-Accept-Language: en MIME-Version: 1.0 To: Eric Dumazet CC: Ulrich Drepper , Andi Kleen , Ravikiran G Thirumalai , "Shai Fultheim (Shai@scalex86.org)" , pravin b shelar , linux-kernel@vger.kernel.org Subject: Re: [RFC] NUMA futex hashing References: <20060808070708.GA3931@localhost.localdomain> <44D8A9BE.3050607@yahoo.com.au> <200608081808.34708.dada1@cosmosbay.com> In-Reply-To: <200608081808.34708.dada1@cosmosbay.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 909 Lines: 23 Eric Dumazet wrote: > We certainly can. But if you insist of using mmap sem at all, then we have a > problem. > > rbtree would not reduce cacheline bouncing, so : > > We could use a hashtable (allocated on demand) of size N, N depending on > NR_CPUS for example. each chain protected by a private spinlock. If N is well > chosen, we might reduce lock cacheline bouncing. (different threads fighting > on different private futexes would have a good chance to get different > cachelines in this hashtable) See other mail. We already have a hash table ;) -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/