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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no 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 1CD06C76195 for ; Thu, 18 Jul 2019 08:13:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F30602173B for ; Thu, 18 Jul 2019 08:13:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727584AbfGRINc (ORCPT ); Thu, 18 Jul 2019 04:13:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56600 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726000AbfGRINc (ORCPT ); Thu, 18 Jul 2019 04:13:32 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4632946288; Thu, 18 Jul 2019 08:13:32 +0000 (UTC) Received: from redhat.com (ovpn-120-147.rdu2.redhat.com [10.10.120.147]) by smtp.corp.redhat.com (Postfix) with SMTP id 778515D720; Thu, 18 Jul 2019 08:13:27 +0000 (UTC) Date: Thu, 18 Jul 2019 04:13:26 -0400 From: "Michael S. Tsirkin" To: Stefano Garzarella Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Stefan Hajnoczi , "David S. Miller" , virtualization@lists.linux-foundation.org, Jason Wang , kvm@vger.kernel.org Subject: Re: [PATCH v4 4/5] vhost/vsock: split packets to send using multiple buffers Message-ID: <20190718041234-mutt-send-email-mst@kernel.org> References: <20190717113030.163499-1-sgarzare@redhat.com> <20190717113030.163499-5-sgarzare@redhat.com> <20190717105336-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Thu, 18 Jul 2019 08:13:32 +0000 (UTC) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, Jul 18, 2019 at 09:50:14AM +0200, Stefano Garzarella wrote: > On Wed, Jul 17, 2019 at 4:55 PM Michael S. Tsirkin wrote: > > > > On Wed, Jul 17, 2019 at 01:30:29PM +0200, Stefano Garzarella wrote: > > > If the packets to sent to the guest are bigger than the buffer > > > available, we can split them, using multiple buffers and fixing > > > the length in the packet header. > > > This is safe since virtio-vsock supports only stream sockets. > > > > > > Signed-off-by: Stefano Garzarella > > > > So how does it work right now? If an app > > does sendmsg with a 64K buffer and the other > > side publishes 4K buffers - does it just stall? > > Before this series, the 64K (or bigger) user messages was split in 4K packets > (fixed in the code) and queued in an internal list for the TX worker. > > After this series, we will queue up to 64K packets and then it will be split in > the TX worker, depending on the size of the buffers available in the > vring. (The idea was to allow EWMA or a configuration of the buffers size, but > for now we postponed it) Got it. Using workers for xmit is IMHO a bad idea btw. Why is it done like this? > Note: virtio-vsock only supports stream socket for now. > > Thanks, > Stefano