From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [PATCH 2/4] Convert epoll to a bitlock Date: Tue, 3 Feb 2009 13:39:42 -0800 Message-ID: <20090203133942.2ecec281.akpm@linux-foundation.org> References: <1233598811-6871-1-git-send-email-corbet@lwn.net> <1233598811-6871-3-git-send-email-corbet@lwn.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1233598811-6871-3-git-send-email-corbet-T1hC0tSOHrs@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, andi-Vw/NltI1exuRpAAqCnN02g@public.gmane.org, oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, viro-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org, davidel-AhlLAIvw+VEjIGhXcJzhZg@public.gmane.org, davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org, hch-jcswGhMUV9g@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, mpm-VDJrAJ4Gl5ZBDgjK7y7TUQ@public.gmane.org, alan-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org, corbet-T1hC0tSOHrs@public.gmane.org List-Id: linux-api@vger.kernel.org On Mon, 2 Feb 2009 11:20:09 -0700 Jonathan Corbet wrote: > Matt Mackall suggested converting epoll's ep_lock to a bitlock as a way of > saving space in struct file. This patch makes that change. hrm. bit_spin_lock() makes people upset (large penguiny people). iirc it doesn't have all the correct/well-understood memory/compiler ordering semantics which spinlocks have. And lockdep doesn't know about it. -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755269AbZBCVkq (ORCPT ); Tue, 3 Feb 2009 16:40:46 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751500AbZBCVkh (ORCPT ); Tue, 3 Feb 2009 16:40:37 -0500 Received: from smtp1.linux-foundation.org ([140.211.169.13]:37488 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751391AbZBCVkh (ORCPT ); Tue, 3 Feb 2009 16:40:37 -0500 Date: Tue, 3 Feb 2009 13:39:42 -0800 From: Andrew Morton To: Jonathan Corbet Cc: linux-kernel@vger.kernel.org, andi@firstfloor.org, oleg@redhat.com, viro@ZenIV.linux.org.uk, davidel@xmailserver.org, davem@davemloft.net, hch@lst.de, linux-api@vger.kernel.org, mpm@selenic.com, alan@lxorguk.ukuu.org.uk, corbet@lwn.net Subject: Re: [PATCH 2/4] Convert epoll to a bitlock Message-Id: <20090203133942.2ecec281.akpm@linux-foundation.org> In-Reply-To: <1233598811-6871-3-git-send-email-corbet@lwn.net> References: <1233598811-6871-1-git-send-email-corbet@lwn.net> <1233598811-6871-3-git-send-email-corbet@lwn.net> X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.20; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2 Feb 2009 11:20:09 -0700 Jonathan Corbet wrote: > Matt Mackall suggested converting epoll's ep_lock to a bitlock as a way of > saving space in struct file. This patch makes that change. hrm. bit_spin_lock() makes people upset (large penguiny people). iirc it doesn't have all the correct/well-understood memory/compiler ordering semantics which spinlocks have. And lockdep doesn't know about it.