Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S933497AbcK1RBo (ORCPT <rfc822;w@1wt.eu>);
        Mon, 28 Nov 2016 12:01:44 -0500
Received: from mx0a-0016f401.pphosted.com ([67.231.148.174]:49664 "EHLO
        mx0b-0016f401.pphosted.com" rhost-flags-OK-OK-OK-FAIL)
        by vger.kernel.org with ESMTP id S933442AbcK1RBb (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Mon, 28 Nov 2016 12:01:31 -0500
Subject: Re: stmmac ethernet in kernel 4.4: coalescing related pauses?
To: David Miller <davem@davemloft.net>
References: <20161128.095431.856183735501262965.davem@davemloft.net>
 <1480347103.18162.58.camel@edumazet-glaptop3.roam.corp.google.com>
 <920b1148-a77d-0b69-01b0-b14bcbdf8648@marvell.com>
 <20161128.113031.964579744326063048.davem@davemloft.net>
CC: <eric.dumazet@gmail.com>, <pavel@ucw.cz>, <peppe.cavallaro@st.com>,
        <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>
From: Lino Sanfilippo <lsanfil@marvell.com>
Message-ID: <279bb203-486f-7086-e232-ed3e1cb0af2f@marvell.com>
Date: Mon, 28 Nov 2016 18:01:10 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101
 Thunderbird/45.4.0
MIME-Version: 1.0
In-Reply-To: <20161128.113031.964579744326063048.davem@davemloft.net>
Content-Type: text/plain; charset="windows-1252"; format=flowed
Content-Transfer-Encoding: 7bit
X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-11-28_14:,,
 signatures=0
X-Proofpoint-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501
 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0
 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0
 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1609300000
 definitions=main-1611280279
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 575
Lines: 19



On 28.11.2016 17:30, David Miller wrote:
> From: Lino Sanfilippo <lsanfil@marvell.com>
> Date: Mon, 28 Nov 2016 16:57:35 +0100
>
>> I wonder if the best fix would be indeed to deactivate irq coalescing
>> completely.
>> Does it make any sense at all to use it if a driver uses NAPI already?
>
> It absolutely does make sense, when it is implemented and functions
> properly.
>

Interesting. I always thought both (NAPI and irq coalescing) are essentially doing the same thing only
one time in software and one time with hw support. Did I misunderstand NAPI?

Regards,
Lino