From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755343AbbAaLIB (ORCPT ); Sat, 31 Jan 2015 06:08:01 -0500 Received: from ou.quest-ce.net ([195.154.187.82]:45812 "EHLO ou.quest-ce.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754315AbbAaLH6 (ORCPT ); Sat, 31 Jan 2015 06:07:58 -0500 Message-ID: <1422702466.3030.4.camel@opteya.com> From: Yann Droneaud To: Rasmus Villemoes Cc: Roland Dreier , Sean Hefty , Hal Rosenstock , linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org, Devesh Sharma , Selvin Xavier , Mitesh Ahuja Date: Sat, 31 Jan 2015 12:07:46 +0100 In-Reply-To: <87twz7ho25.fsf@rasmusvillemoes.dk> References: <1421419196-4659-1-git-send-email-linux@rasmusvillemoes.dk> <87twz7ho25.fsf@rasmusvillemoes.dk> Organization: OPTEYA Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.10 (3.12.10-1.fc21) Mime-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 2001:67c:1810:f0ff:8e70:5aff:fe2f:2d74 X-SA-Exim-Mail-From: ydroneaud@opteya.com Subject: Re: [PATCH 1/2] infiniband: Help gcc generate better code for ocrdma_srq_toggle_bit X-SA-Exim-Version: 4.2.1 (built Mon, 26 Dec 2011 16:24:06 +0000) X-SA-Exim-Scanned: Yes (on ou.quest-ce.net) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Le samedi 31 janvier 2015 à 00:00 +0100, Rasmus Villemoes a écrit : > ping > As you're fixing ocrdma driver, I think you might want to find people @emulex.com to review your patches. BTW, there's no MAINTAINERS entry for ocrdma driver ... which is a pity. > On Fri, Jan 16 2015, Rasmus Villemoes wrote: > > > gcc emits a surprising amount of code in order to flip a bit. One > > would think that a single instruction is enough. > > > > $ scripts/bloat-o-meter /tmp/ocrdma_verbs.o drivers/infiniband/hw/ocrdma/ocrdma_verbs.o > > add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-142 (-142) > > function old new delta > > ocrdma_post_srq_recv 498 460 -38 > > ocrdma_poll_cq 2010 1962 -48 > > ocrdma_discard_cqes 495 439 -56 > > > > All three calls of ocrdma_srq_toggle_bit happen within spinlocks, so > > saving a few useless instructions might be worthwhile. > > > > Signed-off-by: Rasmus Villemoes > > --- > > drivers/infiniband/hw/ocrdma/ocrdma_verbs.c | 5 +---- > > 1 file changed, 1 insertion(+), 4 deletions(-) > > > > diff --git a/drivers/infiniband/hw/ocrdma/ocrdma_verbs.c b/drivers/infiniband/hw/ocrdma/ocrdma_verbs.c > > index fb8d8c4dfbb9..eff11e6c6183 100644 > > --- a/drivers/infiniband/hw/ocrdma/ocrdma_verbs.c > > +++ b/drivers/infiniband/hw/ocrdma/ocrdma_verbs.c > > @@ -1484,10 +1484,7 @@ static void ocrdma_srq_toggle_bit(struct ocrdma_srq *srq, int idx) > > int i = idx / 32; > > unsigned int mask = (1 << (idx % 32)); > > > > - if (srq->idx_bit_fields[i] & mask) > > - srq->idx_bit_fields[i] &= ~mask; > > - else > > - srq->idx_bit_fields[i] |= mask; > > + srq->idx_bit_fields[i] ^= mask; > > } > > > > static int ocrdma_hwq_free_cnt(struct ocrdma_qp_hwq_info *q) > -- Regards. -- Yann Droneaud OPTEYA