From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933092Ab3CVCBy (ORCPT ); Thu, 21 Mar 2013 22:01:54 -0400 Received: from mail.openrapids.net ([64.15.138.104]:53680 "EHLO blackscsi.openrapids.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932265Ab3CVCBx (ORCPT ); Thu, 21 Mar 2013 22:01:53 -0400 Date: Thu, 21 Mar 2013 22:01:50 -0400 From: Mathieu Desnoyers To: Eric Wong Cc: Lai Jiangshan , "Paul E. McKenney" , Stephen Hemminger , Davide Libenzi , linux-kernel@vger.kernel.org Subject: Re: [PATCH] wfcqueue: functions for local append and enqueue Message-ID: <20130322020150.GA17809@Krystal> References: <20130311213602.GB9829@Krystal> <20130321114313.GA17275@dcvr.yhbt.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130321114313.GA17275@dcvr.yhbt.net> X-Editor: vi X-Info: http://www.efficios.com User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Eric Wong (normalperson@yhbt.net) wrote: > With level-triggered epoll, append/enqueue operations to the > local/locked queues increase performance by avoiding unnecessary atomic > operations and barriers. These are necessary to avoid performance > regressions when looping through ep_send_events and appending many > items to a queue. Sounds like a good idea, > > Signed-off-by: Eric Wong > Cc: Mathieu Desnoyers > Cc: Lai Jiangshan > Cc: Paul E. McKenney > Cc: Stephen Hemminger > Cc: Davide Libenzi > --- > Benchmark for this coming with updated epoll patches. > > include/linux/wfcqueue.h | 43 +++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 43 insertions(+) > > diff --git a/include/linux/wfcqueue.h b/include/linux/wfcqueue.h > index 9464a0c..7eb2aaa 100644 > --- a/include/linux/wfcqueue.h > +++ b/include/linux/wfcqueue.h > @@ -205,6 +205,49 @@ static inline bool wfcq_enqueue(struct wfcq_head *head, > } > > /* > + * __wfcq_append_local: append one local queue to another local queue > + * > + * No memory barriers are issued. Mutual exclusion is the responsibility > + * of the caller. > + * > + * Returns false if the queue was empty prior to adding the node. > + * Returns true otherwise. > + */ > +static inline bool __wfcq_append_local(struct wfcq_head *head, Following the rest of the header, we could use: ___wfcq_append() for this function, > + struct wfcq_tail *tail, > + struct wfcq_node *new_head, > + struct wfcq_node *new_tail) > +{ > + struct wfcq_node *old_tail; > + > + old_tail = tail->p; > + tail->p = new_tail; > + old_tail->next = new_head; > + > + /* > + * Return false if queue was empty prior to adding the node, > + * else return true. > + */ > + return old_tail != &head->node; > +} > + > +/* > + * wfcq_enqueue_local: enqueue a node into a local wait-free queue > + * > + * No memory barriers are issued. Mutual exclusion is the responsibility > + * of the caller. > + * > + * Returns false if the queue was empty prior to adding the node. > + * Returns true otherwise. > + */ > +static inline bool wfcq_enqueue_local(struct wfcq_head *head, and: __wfcq_enqueue() we should also update the "Synchronization table" at the beginning of the file accordingly. Thoughts ? Thanks, Mathieu > + struct wfcq_tail *tail, > + struct wfcq_node *new_tail) > +{ > + return __wfcq_append_local(head, tail, new_tail, new_tail); > +} > + > +/* > * ___wfcq_busy_wait: busy-wait. > */ > static inline void ___wfcq_busy_wait(void) > -- > 1.8.2.rc3.2.g89ce8d6 > -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com