From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757932Ab1I3X4h (ORCPT ); Fri, 30 Sep 2011 19:56:37 -0400 Received: from mail-iy0-f174.google.com ([209.85.210.174]:38736 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754301Ab1I3X4a (ORCPT ); Fri, 30 Sep 2011 19:56:30 -0400 Date: Fri, 30 Sep 2011 16:56:25 -0700 From: Tejun Heo To: Matt Fleming Cc: Oleg Nesterov , linux-kernel@vger.kernel.org, Tony Luck Subject: Re: [RFC][PATCH 0/5] Signal scalability series Message-ID: <20110930235625.GD2658@mtj.dyndns.org> References: <1317395577-14091-1-git-send-email-matt@console-pimps.org> <20110930165206.GA22048@redhat.com> <1317412823.3375.34.camel@mfleming-mobl1.ger.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1317412823.3375.34.camel@mfleming-mobl1.ger.corp.intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Fri, Sep 30, 2011 at 09:00:23PM +0100, Matt Fleming wrote: > On Fri, 2011-09-30 at 18:52 +0200, Oleg Nesterov wrote: > Well, sighand->siglock is seriously overused. It protects so much and I > think it's pretty confusing. It took me long enough to figure out how > many locks were really needed. But that's beside the point, having a > single lock doesn't scale at all, and that's what this series is about. But scalability for what? What are the use cases here? Do we care enough about benefits to those use cases to accept the increased complexity? Having locks with broad coverage isn't necessarily evil. If things are simpler that way and the protected paths aren't that hot, who cares? If splitting the locking makes things simpler, sure but that doesn't look like the case here, so we need pretty strong rationale to justify the added complexity. Thank you. -- tejun