From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: Kernel rwlock design, Multicore and IGMP Date: Sat, 13 Nov 2010 23:53:46 +0100 Message-ID: <1289688826.2109.400.camel@laptop> References: <1289489007.17691.1310.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Cc: Eric Dumazet , linux-kernel@vger.kernel.org, netdev To: Cypher Wu Return-path: Received: from casper.infradead.org ([85.118.1.10]:51984 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754348Ab0KMWxb convert rfc822-to-8bit (ORCPT ); Sat, 13 Nov 2010 17:53:31 -0500 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Fri, 2010-11-12 at 11:32 +0800, Cypher Wu wrote: > It seems not a problem that read_lock() can be nested or not since > rwlock doesn't have 'owner', You're mistaken. > it's just that should we give > write_lock() a priority than read_lock() since if there have a lot > read_lock()s then they'll starve write_lock(). We rely on that behaviour. FWIW write preference locks will starve readers. > We should work out a well defined behavior so all the > platform-dependent raw_rwlock has to design under that principle. We have that, all archs have read preference rwlock_t, they have to, code relies on it.