> From: devel [mailto:driverdev-devel-boun...@linuxdriverproject.org] On Behalf > Of Dexuan Cui > Sent: Tuesday, May 17, 2016 10:46 > To: David Miller <da...@davemloft.net> > Cc: o...@aepfle.de; gre...@linuxfoundation.org; jasow...@redhat.com; > linux-kernel@vger.kernel.org; j...@perches.com; net...@vger.kernel.org; > a...@canonical.com; de...@linuxdriverproject.org; Haiyang Zhang > <haiya...@microsoft.com> > Subject: RE: [PATCH v11 net-next 0/1] introduce Hyper-V VM Sockets(hv_sock) > > > From: David Miller [mailto:da...@davemloft.net] > > Sent: Monday, May 16, 2016 1:16 > > To: Dexuan Cui <de...@microsoft.com> > > Cc: gre...@linuxfoundation.org; net...@vger.kernel.org; linux- > > ker...@vger.kernel.org; de...@linuxdriverproject.org; o...@aepfle.de; > > a...@canonical.com; jasow...@redhat.com; cav...@redhat.com; KY > > Srinivasan <k...@microsoft.com>; Haiyang Zhang <haiya...@microsoft.com>; > > j...@perches.com; vkuzn...@redhat.com > > Subject: Re: [PATCH v11 net-next 0/1] introduce Hyper-V VM Sockets(hv_sock) > > > > From: Dexuan Cui <de...@microsoft.com> > > Date: Sun, 15 May 2016 09:52:42 -0700 > > > > > Changes since v10 > > > > > > 1) add module params: send_ring_page, recv_ring_page. They can be used > to > > > enlarge the ringbuffer size to get better performance, e.g., > > > # modprobe hv_sock recv_ring_page=16 send_ring_page=16 > > > By default, recv_ring_page is 3 and send_ring_page is 2. > > > > > > 2) add module param max_socket_number (the default is 1024). > > > A user can enlarge the number to create more than 1024 hv_sock sockets. > > > By default, 1024 sockets take about 1024 * (3+2+1+1) * 4KB = 28M bytes. > > > (Here 1+1 means 1 page for send/recv buffers per connection, > > > respectively.) > > > > This is papering around my objections, and create module parameters which > > I am fundamentally against. > > > > You're making the facility unusable by default, just to work around my > > memory consumption concerns. > > > > What will end up happening is that everyone will simply increase the > > values. > > > > You're not really addressing the core issue, and I will be ignoring you > > future submissions of this change until you do. > > David, > I am sorry I came across as ignoring your feedback; that was not my intention. > The current host side design for this feature is such that each socket > connection > needs its own channel, which consists of > > 1. A ring buffer for host to guest communication > 2. A ring buffer for guest to host communication > > The memory for the ring buffers has to be pinned down as this will be accessed > both from interrupt level in Linux guest and from the host OS at any time. > > To address your concerns, I am planning to re-implement both the receive path > and the send path so that no additional pinned memory will be needed. > > Receive Path: > When the application does a read on the socket, we will dynamically allocate > the buffer and perform the read operation on the incoming ring buffer. Since > we will be in the process context, we can sleep here and will set the > "GFP_KERNEL | __GFP_NOFAIL" flags. This buffer will be freed once the > application consumes all the data. > > Send Path: > On the send side, we will construct the payload to be sent directly on the > outgoing ringbuffer. > > So, with these changes, the only memory that will be pinned down will be the > memory for the ring buffers on a per-connection basis and this memory will be > pinned down until the connection is torn down. > > Please let me know if this addresses your concerns. > > -- Dexuan
Hi David, Ping. Really appreciate your comment. Thanks, -- Dexuan
