Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751117AbVLGPkX (ORCPT ); Wed, 7 Dec 2005 10:40:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751139AbVLGPkX (ORCPT ); Wed, 7 Dec 2005 10:40:23 -0500 Received: from pentafluge.infradead.org ([213.146.154.40]:37869 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S1751117AbVLGPkX (ORCPT ); Wed, 7 Dec 2005 10:40:23 -0500 Subject: Re: [linux-usb-devel] Re: [PATCH 00/10] usb-serial: Switches from spin lock to atomic_t. From: Arjan van de Ven To: Oliver Neukum Cc: Alan Stern , linux-usb-devel@lists.sourceforge.net, Eduardo Pereira Habkost , Greg KH , Luiz Fernando Capitulino , linux-kernel@vger.kernel.org In-Reply-To: <200512071637.40018.oliver@neukum.org> References: <1133968943.2869.26.camel@laptopd505.fenrus.org> <200512071637.40018.oliver@neukum.org> Content-Type: text/plain Date: Wed, 07 Dec 2005 16:40:14 +0100 Message-Id: <1133970015.2869.31.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit X-Spam-Score: 1.8 (+) X-Spam-Report: SpamAssassin version 3.0.4 on pentafluge.infradead.org summary: Content analysis details: (1.8 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- 0.1 RCVD_IN_SORBS_DUL RBL: SORBS: sent directly from dynamic IP address [213.93.14.173 listed in dnsbl.sorbs.net] 1.7 RCVD_IN_NJABL_DUL RBL: NJABL: dialup sender did non-local SMTP [213.93.14.173 listed in combined.njabl.org] X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 893 Lines: 20 On Wed, 2005-12-07 at 16:37 +0100, Oliver Neukum wrote: > Am Mittwoch, 7. Dezember 2005 16:22 schrieb Arjan van de Ven: > > > On the other hand, Oliver needs to be careful about claiming too much. In > > > general atomic_t operations _are_ superior to the spinlock approach. > > > > No they're not. Both are just about equally expensive cpu wise, > > sometimes the atomic_t ones are a bit more expensive (like on parisc > > architecture). But on x86 in either case it's a locked cycle, which is > > just expensive no matter which side you flip the coin... > > You are refering to SMP, aren't you? yes. on UP neither is a locked instruction ;) - 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/