Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751322AbbEZSmo (ORCPT ); Tue, 26 May 2015 14:42:44 -0400 Received: from cantor2.suse.de ([195.135.220.15]:39234 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750854AbbEZSml (ORCPT ); Tue, 26 May 2015 14:42:41 -0400 Message-ID: <1432665731.8196.3.camel@stgolabs.net> Subject: Re: [RFC][PATCH 0/5] Optimize percpu-rwsem From: Davidlohr Bueso To: Linus Torvalds Cc: Peter Zijlstra , Oleg Nesterov , Paul McKenney , Tejun Heo , Ingo Molnar , Linux Kernel Mailing List , der.herr@hofr.at Date: Tue, 26 May 2015 11:42:11 -0700 In-Reply-To: References: <20150526114356.609107918@infradead.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.11 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1078 Lines: 30 On Tue, 2015-05-26 at 11:12 -0700, Linus Torvalds wrote: > On Tue, May 26, 2015 at 4:43 AM, Peter Zijlstra wrote: > > > > This is a derived work of the cpu hotplug lock rework I did in 2013 which never > > really went anywhere because Linus didn't like it. > > > > This applies those same optimizations to the percpu-rwsem. Seeing how we did > > all the work it seemed a waste to not use it at all. > > So I *still* don't like it. > > We literally have one single percpu-rwsem IN THE WHOLE KERNEL TREE. > > One. > > Not "a couple". Not "hundreds". ONE. Instead of dropping percpu-rwsem, I was thinking we could instead look for opportunities to convert new users, for instance shinkers, where the write lock is also taken just for register and unregister purposes, similar to uprobes. Thanks, Davidlohr -- 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/