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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 D41F8C3A5A7 for ; Mon, 2 Sep 2019 15:01:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B47D321744 for ; Mon, 2 Sep 2019 15:01:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731801AbfIBPB6 (ORCPT ); Mon, 2 Sep 2019 11:01:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60294 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731725AbfIBPB5 (ORCPT ); Mon, 2 Sep 2019 11:01:57 -0400 Received: from mail-qt1-f197.google.com (mail-qt1-f197.google.com [209.85.160.197]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 12E4D155DB for ; Mon, 2 Sep 2019 15:01:57 +0000 (UTC) Received: by mail-qt1-f197.google.com with SMTP id i19so15856919qtq.17 for ; Mon, 02 Sep 2019 08:01:57 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=3eUULgrjIJg0a0dnW4SKY8dVu/LzudzFut/uYLoCkM0=; b=O3iXFgTPBf1Ir92Cr0BcLvoPChE3rpNKZlaguATmkJ7GJZ0s0NDTgZmn+OrJErbRb/ 4AaO2DXwerlAcFgzRUDHudShNOiP+24ANIBfYV7z7ycxTHfcGt8BRoVnasFsajEBH8qi OeVCdacOQRTKFy28tdNNEv9IkNJuPo+euU6UBwuyI5+fRhogZJWLcbS0riTCBH3C3iYM 5fOEhtalWBLVoiUwSpv02RsUZO/0tKfAHb2/wNysMfYg090PePGS54NBQa4TiILm6+Az Hb5+BdogKWiN4GuECFJVYWEP3vyPxz3dVOjl9JyGiPNgZLZ3ca+tVlIGQrAcvfw0OKEX VmqA== X-Gm-Message-State: APjAAAW9WsGxpTH5oOBzbSat0fnENSegdvtVVnbgf7IXtpac8u6oGScz KH3ftmdRnT1qH4W2ebSDTcuRjCyhV9thFWqP8kYzGc/VyGLZAJ60EgOmHVglZumvi+84Ch2/dnI D+j00sSygDWGRODHR X-Received: by 2002:ac8:750e:: with SMTP id u14mr28909664qtq.282.1567436516418; Mon, 02 Sep 2019 08:01:56 -0700 (PDT) X-Google-Smtp-Source: APXvYqzukZkbHkn1xgGj19iRwoWTZ0EUi0+QeIBA4njsNuROpWrZ/97Kw7ZdMd2ZPPImX2/1Fxx4Fg== X-Received: by 2002:ac8:750e:: with SMTP id u14mr28909631qtq.282.1567436516228; Mon, 02 Sep 2019 08:01:56 -0700 (PDT) Received: from redhat.com (bzq-79-180-62-110.red.bezeqint.net. [79.180.62.110]) by smtp.gmail.com with ESMTPSA id o11sm4589103qkm.105.2019.09.02.08.01.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Sep 2019 08:01:55 -0700 (PDT) Date: Mon, 2 Sep 2019 11:01:48 -0400 From: "Michael S. Tsirkin" To: ? jiang Cc: "jasowang@redhat.com" , "davem@davemloft.net" , "ast@kernel.org" , "daniel@iogearbox.net" , "jakub.kicinski@netronome.com" , "hawk@kernel.org" , "john.fastabend@gmail.com" , "kafai@fb.com" , "songliubraving@fb.com" , "yhs@fb.com" , "virtualization@lists.linux-foundation.org" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "xdp-newbies@vger.kernel.org" , "bpf@vger.kernel.org" , "jiangran.jr@alibaba-inc.com" Subject: Re: [PATCH v3] virtio-net: lower min ring num_free for efficiency Message-ID: <20190902110038-mutt-send-email-mst@kernel.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, Aug 20, 2019 at 02:51:23AM +0000, ? jiang wrote: > This change lowers ring buffer reclaim threshold from 1/2*queue to budget > for better performance. According to our test with qemu + dpdk, packet > dropping happens when the guest is not able to provide free buffer in > avail ring timely with default 1/2*queue. The value in the patch has been > tested and does show better performance. > > Test setup: iperf3 to generate packets to guest (total 30mins, pps 400k, UDP) > avg packets drop before: 2842 > avg packets drop after: 360(-87.3%) > > Further, current code suffers from a starvation problem: the amount of > work done by try_fill_recv is not bounded by the budget parameter, thus > (with large queues) once in a while userspace gets blocked for a long > time while queue is being refilled. Trigger refills earlier to make sure > the amount of work to do is limited. > > Signed-off-by: jiangkidd > Acked-by: Jason Wang > Acked-by: Michael S. Tsirkin Dave, could you merge this please? Either net or net-next at your discretion. > --- > drivers/net/virtio_net.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 0d4115c9e20b..bc08be7925eb 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -1331,7 +1331,7 @@ static int virtnet_receive(struct receive_queue *rq, int budget, > } > } > > - if (rq->vq->num_free > virtqueue_get_vring_size(rq->vq) / 2) { > + if (rq->vq->num_free > min((unsigned int)budget, virtqueue_get_vring_size(rq->vq)) / 2) { > if (!try_fill_recv(vi, rq, GFP_ATOMIC)) > schedule_delayed_work(&vi->refill, 0); > } > -- > 2.11.0