From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Eilon Greenstein" Subject: [PATCH 03/18] bnx2x: Reduce the likelihood of smb_mb Date: Mon, 02 Mar 2009 19:59:24 +0200 Message-ID: <1236016764.7723.74.camel@lb-tlvb-eliezer> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: "David Miller" Return-path: Received: from mms1.broadcom.com ([216.31.210.17]:2320 "EHLO mms1.broadcom.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755602AbZCBSAO (ORCPT ); Mon, 2 Mar 2009 13:00:14 -0500 Sender: netdev-owner@vger.kernel.org List-ID: Subject: [PATCH 03/18] bnx2x: Reduce the likelihood of smb_mb As the comment explains, this smb_mb is needed only if the queue is stopped (which is unlikely) so the barrier can be moved to that location Signed-off-by: Eilon Greenstein --- drivers/net/bnx2x_main.c | 15 ++++++++------- 1 files changed, 8 insertions(+), 7 deletions(-) diff --git a/drivers/net/bnx2x_main.c b/drivers/net/bnx2x_main.c index 5954bed..fbd0f88 100644 --- a/drivers/net/bnx2x_main.c +++ b/drivers/net/bnx2x_main.c @@ -916,18 +916,19 @@ static void bnx2x_tx_int(struct bnx2x_fastpath *fp, int work) fp->tx_pkt_cons = sw_cons; fp->tx_bd_cons = bd_cons; - /* Need to make the tx_bd_cons update visible to start_xmit() - * before checking for netif_tx_queue_stopped(). Without the - * memory barrier, there is a small possibility that start_xmit() - * will miss it and cause the queue to be stopped forever. - */ - smp_mb(); - /* TBD need a thresh? */ if (unlikely(netif_tx_queue_stopped(txq))) { __netif_tx_lock(txq, smp_processor_id()); + /* Need to make the tx_bd_cons update visible to start_xmit() + * before checking for netif_tx_queue_stopped(). Without the + * memory barrier, there is a small possibility that + * start_xmit() will miss it and cause the queue to be stopped + * forever. + */ + smp_mb(); + if ((netif_tx_queue_stopped(txq)) && (bp->state == BNX2X_STATE_OPEN) && (bnx2x_tx_avail(fp) >= MAX_SKB_FRAGS + 3)) -- 1.5.4.3