From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752154AbeEVTaB (ORCPT ); Tue, 22 May 2018 15:30:01 -0400 Received: from userp2130.oracle.com ([156.151.31.86]:58484 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751512AbeEVTaA (ORCPT ); Tue, 22 May 2018 15:30:00 -0400 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 11.4 \(3445.8.2\)) Subject: Re: Regression: Approximate 34% performance hit in receive throughput over ixgbe seen due to build_skb patch From: William Kucharski In-Reply-To: Date: Tue, 22 May 2018 13:29:53 -0600 Cc: LKML , Netdev , intel-wired-lan , Jeff Kirsher , "Duyck, Alexander H" Message-Id: <4F646FBB-FE0B-4FEE-98E5-3CA2DF0598DE@oracle.com> References: To: Alexander Duyck X-Mailer: Apple Mail (2.3445.8.2) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8901 signatures=668700 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=3 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=570 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1711220000 definitions=main-1805220202 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id w4MJU8Jj027665 > On May 22, 2018, at 12:23 PM, Alexander Duyck wrote: > > 3. There should be a private flag that can be updated via "ethtool > --set-priv-flags" called "legacy-rx" that you can enable that will > roll back to the original that did the copy-break type approach for > small packets and the headers of the frame. With legacy-rx enabled, most of the regression goes away, but it's still present as compared to the code without the patch; the regression then drops to about 6%: # ethtool --show-priv-flags eno1 Private flags for eno1: legacy-rx: on Socket Message Elapsed Messages Size Size Time Okay Errors Throughput bytes bytes secs # # 10^6bits/sec 65536 64 60.00 35934709 0 306.64 65536 60.00 33791739 288.35 Socket Message Elapsed Messages Size Size Time Okay Errors Throughput bytes bytes secs # # 10^6bits/sec 65536 64 60.00 39254351 0 334.97 65536 60.00 36761069 313.69 Is this variance to be expected, or do you think modification of the interrupt delay would achieve better results? William Kucharski