From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [RFC] [PATCH v2 3/3] Let host NIC driver to DMA to guest user space. Date: Thu, 8 Apr 2010 17:52:25 -0700 Message-ID: <20100408175225.7577af19@nehalam> References: <1270193410-6877-1-git-send-email-xiaohui.xin@intel.com> <20100402085556.75a8ff7c@nehalam> <97F6D3BD476C464182C1B7BABF0B0AF5C17B5C2A@shzsmsx502.ccr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: "netdev@vger.kernel.org" , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "mingo@elte.hu" , "mst@redhat.com" , "jdike@c2.user-mode-linux.org" , "davem@davemloft.net" To: "Xin, Xiaohui" Return-path: In-Reply-To: <97F6D3BD476C464182C1B7BABF0B0AF5C17B5C2A@shzsmsx502.ccr.corp.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Tue, 6 Apr 2010 14:26:29 +0800 "Xin, Xiaohui" wrote: > >How do you deal with the DoS problem of hostile user space app posting huge > >number of receives and never getting anything. > > That's a problem we are trying to deal with. It's critical for long term. > Currently, we tried to limit the pages it can pin, but not sure how much is reasonable. > For now, the buffers submitted is from guest virtio-net driver, so it's safe in some extent > just for now. It is critical even now. Once you get past toy benchmarks you will see things like Java processes with 1000 threads all reading at once.