From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="iaypeADo" Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 32D3FA7 for ; Tue, 12 Dec 2023 07:54:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1702396463; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Y2h/9XzsjZfgK8E0eqXIAeotqgk7BYzOrlyS+4E0n94=; b=iaypeADoAvDWh0S6XsRoRnCKWJffEsjjmeRz4qtKSBxxOcxPD9+oGhd8Wmw3HDK/Mb+fAZ hpYtiygxZ5C2GWQnv4VdRqhbo+6du3VsY0J/N3yO3Ybu8H38TMGxw9OX2AGry/IKHx186E sfIcDMCMQpmFrX+PT53uFl6Ai/U6OYI= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-411-OCb2llaANCqYTe15Lx1SiQ-1; Tue, 12 Dec 2023 10:54:22 -0500 X-MC-Unique: OCb2llaANCqYTe15Lx1SiQ-1 Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-40c28da6667so36242075e9.3 for ; Tue, 12 Dec 2023 07:54:21 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1702396461; x=1703001261; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=Y2h/9XzsjZfgK8E0eqXIAeotqgk7BYzOrlyS+4E0n94=; b=Qj7j5pb8Eh06oiIZ+v33/7095FNEzE7CvKvDC6u+jgm7IUZ1hLK1pqKMLnYF8W9/H0 +JFDzvgYTa79vOBrz6xxLMTSmCsOXxdZjDt7rdYzo1mQ5pbZYZGEb7IXsZPigly39d+M shsHTgSNia1/6RAcT3h/12fqjgMQYhoHfb1GVk8/X7ae3hxzqHbP8WW/dT6AySeZAYm/ 4a+5KXs7m43ucmoDNN3k/DVzEpe/Uf/elyQOx4O9yW7PyIrB8KX08dgFkHUMM4jqOOBs Dy7KdsxYhtEPJ3OPAvIambkZdCTpCWnbU3D/nt6YDgNbhBMJGtBImRAk0PdovpbceYJE TWUw== X-Gm-Message-State: AOJu0Yy9VWBSB/6BXvJ94rNP1K4PsiS9J7/jpF36q7k9fiov8p6YdgfH gGIb7l4PNUTxaH3OJqpgWmLifmOdQpL137OqF1RAITE/RDAGNxE5tZmT8XqwpYw9W6tOr9pzoR8 kiOqjcr2LO4KIz8PD X-Received: by 2002:a7b:cc82:0:b0:40c:30f8:dce1 with SMTP id p2-20020a7bcc82000000b0040c30f8dce1mr1732744wma.312.1702396460873; Tue, 12 Dec 2023 07:54:20 -0800 (PST) X-Google-Smtp-Source: AGHT+IHJhhRdcg0sgg1jeVxvRyqhKBKMHuUOMmddLacHyE2JT7diifM1UwSyWcZzyvXaXPfNwmicBA== X-Received: by 2002:a7b:cc82:0:b0:40c:30f8:dce1 with SMTP id p2-20020a7bcc82000000b0040c30f8dce1mr1732739wma.312.1702396460534; Tue, 12 Dec 2023 07:54:20 -0800 (PST) Received: from redhat.com ([2.52.23.105]) by smtp.gmail.com with ESMTPSA id b16-20020a5d4b90000000b00336363f1608sm497847wrt.105.2023.12.12.07.54.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 Dec 2023 07:54:19 -0800 (PST) Date: Tue, 12 Dec 2023 10:54:16 -0500 From: "Michael S. Tsirkin" To: Arseniy Krasnov Cc: Stefan Hajnoczi , Stefano Garzarella , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Jason Wang , Bobby Eshleman , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@sberdevices.ru, oxffffaa@gmail.com Subject: Re: [PATCH net-next v8 3/4] virtio/vsock: fix logic which reduces credit update messages Message-ID: <20231212105322-mutt-send-email-mst@kernel.org> References: <20231211211658.2904268-1-avkrasnov@salutedevices.com> <20231211211658.2904268-4-avkrasnov@salutedevices.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231211211658.2904268-4-avkrasnov@salutedevices.com> On Tue, Dec 12, 2023 at 12:16:57AM +0300, Arseniy Krasnov wrote: > Add one more condition for sending credit update during dequeue from > stream socket: when number of bytes in the rx queue is smaller than > SO_RCVLOWAT value of the socket. This is actual for non-default value > of SO_RCVLOWAT (e.g. not 1) - idea is to "kick" peer to continue data > transmission, because we need at least SO_RCVLOWAT bytes in our rx > queue to wake up user for reading data (in corner case it is also > possible to stuck both tx and rx sides, this is why 'Fixes' is used). I don't get what does "to stuck both tx and rx sides" mean. Besides being agrammatical, is there a way to do this without playing with SO_RCVLOWAT? > > Fixes: b89d882dc9fc ("vsock/virtio: reduce credit update messages") > Signed-off-by: Arseniy Krasnov > --- > Changelog: > v6 -> v7: > * Handle wrap of 'fwd_cnt'. > * Do to send credit update when 'fwd_cnt' == 'last_fwd_cnt'. > v7 -> v8: > * Remove unneeded/wrong handling of wrap for 'fwd_cnt'. > > net/vmw_vsock/virtio_transport_common.c | 13 ++++++++++--- > 1 file changed, 10 insertions(+), 3 deletions(-) > > diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c > index e137d740804e..8572f94bba88 100644 > --- a/net/vmw_vsock/virtio_transport_common.c > +++ b/net/vmw_vsock/virtio_transport_common.c > @@ -558,6 +558,8 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk, > struct virtio_vsock_sock *vvs = vsk->trans; > size_t bytes, total = 0; > struct sk_buff *skb; > + u32 fwd_cnt_delta; > + bool low_rx_bytes; > int err = -EFAULT; > u32 free_space; > > @@ -601,7 +603,10 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk, > } > } > > - free_space = vvs->buf_alloc - (vvs->fwd_cnt - vvs->last_fwd_cnt); > + fwd_cnt_delta = vvs->fwd_cnt - vvs->last_fwd_cnt; > + free_space = vvs->buf_alloc - fwd_cnt_delta; > + low_rx_bytes = (vvs->rx_bytes < > + sock_rcvlowat(sk_vsock(vsk), 0, INT_MAX)); > > spin_unlock_bh(&vvs->rx_lock); > > @@ -611,9 +616,11 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk, > * too high causes extra messages. Too low causes transmitter > * stalls. As stalls are in theory more expensive than extra > * messages, we set the limit to a high value. TODO: experiment > - * with different values. > + * with different values. Also send credit update message when > + * number of bytes in rx queue is not enough to wake up reader. > */ > - if (free_space < VIRTIO_VSOCK_MAX_PKT_BUF_SIZE) > + if (fwd_cnt_delta && > + (free_space < VIRTIO_VSOCK_MAX_PKT_BUF_SIZE || low_rx_bytes)) > virtio_transport_send_credit_update(vsk); > > return total; > -- > 2.25.1