From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4B16FC10F13 for ; Thu, 11 Apr 2019 09:16:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E6284217D4 for ; Thu, 11 Apr 2019 09:16:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="SXhBK5ID" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726689AbfDKJQL (ORCPT ); Thu, 11 Apr 2019 05:16:11 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:51822 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725783AbfDKJQK (ORCPT ); Thu, 11 Apr 2019 05:16:10 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Mime-Version:Content-Type:References: In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=D6VR/gQC2XYLyCUNfU2Q051Qwvlxz1ra6Myquhp20js=; b=SXhBK5ID7so2C3wRO9z6ZR2QB N/dkbvnZBWLgtWKzFuxOMrfIegSO7dYoZp/3KqOceAobzxWsYaAtUUj+GPX/lukTmeO3pftDDEHue bRKpC+b0kkMvz0DmGb7/h5FFVS7rpBoBv86FhtELW/pOQAsQVpulotHPpq6Un10ZisLYRpXBpjmV1 D9Xp7jypmixafPLlvkbyjTiFMlIF987KWIfsehyIs4HIVkbJ+dif6nIRRRC6TAGmSapV+FUgdp5Su B/7Gq9iyZ4/MFOryqULdxIFJZfRiIGd9xrl48gAmMpsWVdXhrfOe+UD0h/48nKa5jpre698BOnI9c yxWRVm69Q==; Received: from 54-240-197-239.amazon.com ([54.240.197.239] helo=u3832b3a9db3152.ant.amazon.com) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hEVoX-0002BK-AX; Thu, 11 Apr 2019 09:16:09 +0000 Message-ID: <9c99b79071390729a5b9956fc49822654943c0eb.camel@infradead.org> Subject: Re: Tun congestion/BQL From: David Woodhouse To: Jason Wang , Toke =?ISO-8859-1?Q?H=F8iland-J=F8rgensen?= , netdev@vger.kernel.org Cc: "Michael S. Tsirkin" Date: Thu, 11 Apr 2019 12:16:06 +0300 In-Reply-To: References: <2e310fc6ee847d20dd23692fd1db733e607602f5.camel@infradead.org> <1506fcbbfb7ab7a1e448b7b6cbf45f703bfcc80f.camel@infradead.org> <8c64c80d-165c-076b-fca3-5374edc87853@redhat.com> <87ftqqugbj.fsf@toke.dk> <123cfccb766a6f55312d6a477764d3e7b88ad221.camel@infradead.org> <79f9e78d6f653a4a4ccd2fad76d8c39622491172.camel@infradead.org> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/x-pkcs7-signature"; boundary="=-XFy1Oo0oGpWylnJunrUf" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.1 Mime-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org --=-XFy1Oo0oGpWylnJunrUf Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, 2019-04-11 at 17:04 +0800, Jason Wang wrote: > Btw, forget to mention, I modify your patch to use=20 > netif_stop/wake_subqueue() instead. Hm... --- /usr/src/debug/kernel-5.0.fc29/linux-5.0.5- 200.fc29.x86_64/drivers/net/tun.c2019-03-03 23:21:29.000000000 +0000 +++ /home/fedora/tun/tun.c 2019-04-11 09:11:20.781683956 +0000 @@ -1118,8 +1118,14 @@ static netdev_tx_t tun_net_xmit(struct s =20 nf_reset(skb); =20 - if (ptr_ring_produce(&tfile->tx_ring, skb)) + if (ptr_ring_produce(&tfile->tx_ring, skb)) { + netif_stop_subqueue(tun->dev, txq); goto drop; + } + + if (ptr_ring_full(&tfile->tx_ring)) { + netif_stop_subqueue(tun->dev, txq); + } =20 /* Notify and wake up reader process */ if (tfile->flags & TUN_FASYNC) @@ -2229,6 +2235,8 @@ static ssize_t tun_do_read(struct tun_st consume_skb(skb); } =20 + netif_wake_subqueue(tun->dev, tfile->queue_index); + return ret; } =20 That gives me Socket Message Elapsed Messages =20 Size Size Time Okay Errors Throughput bytes bytes secs # # 10^6bits/sec 212992 1400 10.90 2277474 0 2340.95 212992 10.90 1174728 1207.47 Without the first netif_stop_subqueue() call in the case where we actually *do* drop the packet (which AFAICT should never happen?) it looks like this: Socket Message Elapsed Messages =20 Size Size Time Okay Errors Throughput bytes bytes secs # # 10^6bits/sec 212992 1400 10.00 7675563 0 8596.61 212992 10.00 1441186 1614.13 And without the patch at all, it was still faster when I just let it drop packets: Socket Message Elapsed Messages =20 Size Size Time Okay Errors Throughput bytes bytes secs # # 10^6bits/sec 212992 1400 10.00 8143709 0 9120.93 212992 10.00 1545035 1730.44 --=-XFy1Oo0oGpWylnJunrUf Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCECow ggUcMIIEBKADAgECAhEA4rtJSHkq7AnpxKUY8ZlYZjANBgkqhkiG9w0BAQsFADCBlzELMAkGA1UE BhMCR0IxGzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2FsZm9yZDEaMBgG A1UEChMRQ09NT0RPIENBIExpbWl0ZWQxPTA7BgNVBAMTNENPTU9ETyBSU0EgQ2xpZW50IEF1dGhl 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