From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH] [-MM, FIX V3] e1000e: incorporate napi_struct changes from net-2.6.24.git Date: Wed, 12 Sep 2007 07:53:24 -0700 (PDT) Message-ID: <20070912.075324.98878193.davem@davemloft.net> References: <20070908002730.27700.3774.stgit@localhost.localdomain> <46E1ED43.4070506@intel.com> <18146.21773.295381.108336@robur.slu.se> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: auke-jan.h.kok@intel.com, akpm@linux-foundation.org, jeff@garzik.org, netdev@vger.kernel.org To: Robert.Olsson@data.slu.se Return-path: Received: from 74-93-104-98-Washington.hfc.comcastbusiness.net ([74.93.104.98]:57287 "EHLO picasso.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S965033AbXILOxl (ORCPT ); Wed, 12 Sep 2007 10:53:41 -0400 In-Reply-To: <18146.21773.295381.108336@robur.slu.se> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Robert Olsson Date: Sat, 8 Sep 2007 09:53:49 +0200 > Yes a correct observation. I've spotted this bug too and it caused by the > policy change in the NAPI scheduling. Look at tx_cleaned. > > I suggest we revert this change for now. The tx_cleaned logic change was not intentional, and that's the bug that makes e1000 spin endlessly in NAPI. The other part, the work_done < budget part, was intentional so I'm going to keep it in there for now. I've checked in the patch below to deal with this. I suspect the check "work_done == 0" is some shamans dance to get slightly better performance, but it's 1) wrong and 2) at best needs to be explained in a comment and fully quantified. >>From e8cbb449155000eecc6e855ea71510fecfc7d5ee Mon Sep 17 00:00:00 2001 From: David S. Miller Date: Wed, 12 Sep 2007 16:50:32 +0200 Subject: [PATCH] [E1000]: Fix unintended NAPI breakout logic change. The inversion of the !tx_cleaned test in e1000_clean() was not intentional, we just wanted to change the "work_done == 0" to "work_done < budget" Noticed by Robert Olsson. Signed-off-by: David S. Miller --- drivers/net/e1000/e1000_main.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/drivers/net/e1000/e1000_main.c b/drivers/net/e1000/e1000_main.c index 7b0bcdb..58bb758 100644 --- a/drivers/net/e1000/e1000_main.c +++ b/drivers/net/e1000/e1000_main.c @@ -3944,7 +3944,7 @@ e1000_clean(struct napi_struct *napi, int budget) &work_done, budget); /* If no Tx and not enough Rx work done, exit the polling mode */ - if ((tx_cleaned && (work_done < budget)) || + if ((!tx_cleaned && (work_done < budget)) || !netif_running(poll_dev)) { quit_polling: if (likely(adapter->itr_setting & 3)) -- 1.5.2.4