From patchwork Mon Apr 6 11:39:32 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Konstantin Khlebnikov X-Patchwork-Id: 1266825 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=yandex-team.ru Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=yandex-team.ru header.i=@yandex-team.ru header.a=rsa-sha256 header.s=default header.b=0IKqwrP0; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 48wpVQ5RJlz9sRY for ; Mon, 6 Apr 2020 21:39:42 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727481AbgDFLjh (ORCPT ); Mon, 6 Apr 2020 07:39:37 -0400 Received: from forwardcorp1j.mail.yandex.net ([5.45.199.163]:45844 "EHLO forwardcorp1j.mail.yandex.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727192AbgDFLjg (ORCPT ); Mon, 6 Apr 2020 07:39:36 -0400 Received: from mxbackcorp1o.mail.yandex.net (mxbackcorp1o.mail.yandex.net [IPv6:2a02:6b8:0:1a2d::301]) by forwardcorp1j.mail.yandex.net (Yandex) with ESMTP id A35072E14E8; Mon, 6 Apr 2020 14:39:33 +0300 (MSK) Received: from myt4-18a966dbd9be.qloud-c.yandex.net (myt4-18a966dbd9be.qloud-c.yandex.net [2a02:6b8:c00:12ad:0:640:18a9:66db]) by mxbackcorp1o.mail.yandex.net (mxbackcorp/Yandex) with ESMTP id sX88qFixUn-dXiqsfHL; Mon, 06 Apr 2020 14:39:33 +0300 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1586173173; bh=Udgck5hZl7iY8rk7tJBnajnqAtzBoXXAebBFLAw1OM8=; h=Message-ID:Date:To:From:Subject:Cc; b=0IKqwrP0baovIK3RCualDi6GobR3G3k/do+aWVt0ZSJFwKoIV9r1UU4OnMtkPlCHm XCIRM12rKidSHVVoYSArzG+p1ruaguPHCNoCtplLqNfpVaCxmqoNrxa8z2DnKcs7Ae dUjehR169vpBHIAtzv13cL6MWuvG71j7Nl/WyNvA= Authentication-Results: mxbackcorp1o.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Received: from unknown (unknown [2a02:6b8:b080:6407::1:5]) by myt4-18a966dbd9be.qloud-c.yandex.net (smtpcorp/Yandex) with ESMTPSA id FtB5uheCc4-dWW40PVT; Mon, 06 Apr 2020 14:39:32 +0300 (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client certificate not present) Subject: [PATCH] net: revert default NAPI poll timeout to 2 jiffies From: Konstantin Khlebnikov To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Jakub Kicinski , Dmitry Yakunin , "David S. Miller" , Matthew Whitehead Date: Mon, 06 Apr 2020 14:39:32 +0300 Message-ID: <158617317267.1170.12944758673162826206.stgit@buzz> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org For HZ < 1000 timeout 2000us rounds up to 1 jiffy but expires randomly because next timer interrupt could come shortly after starting softirq. For commonly used CONFIG_HZ=1000 nothing changes. Fixes: 7acf8a1e8a28 ("Replace 2 jiffies with sysctl netdev_budget_usecs to enable softirq tuning") Reported-by: Dmitry Yakunin Signed-off-by: Konstantin Khlebnikov --- net/core/dev.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/core/dev.c b/net/core/dev.c index 9c9e763bfe0e..df8097b8e286 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4140,7 +4140,8 @@ EXPORT_SYMBOL(netdev_max_backlog); int netdev_tstamp_prequeue __read_mostly = 1; int netdev_budget __read_mostly = 300; -unsigned int __read_mostly netdev_budget_usecs = 2000; +/* Must be at least 2 jiffes to guarantee 1 jiffy timeout */ +unsigned int __read_mostly netdev_budget_usecs = 2 * USEC_PER_SEC / HZ; int weight_p __read_mostly = 64; /* old backlog weight */ int dev_weight_rx_bias __read_mostly = 1; /* bias for backlog weight */ int dev_weight_tx_bias __read_mostly = 1; /* bias for output_queue quota */