From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ivan Boule Subject: Re: [RFC PATCH 0/5] Introduce low-latency one-shot rx interrupt into DPDK with polling/interrupt switch control example Date: Fri, 23 Jan 2015 10:22:11 +0100 Message-ID: <54C212C3.7060604@6wind.com> References: <1421747640-20978-1-git-send-email-danny.zhou@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit To: Danny Zhou , dev-VfR2kkLFssw@public.gmane.org Return-path: In-Reply-To: <1421747640-20978-1-git-send-email-danny.zhou-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces-VfR2kkLFssw@public.gmane.org Sender: "dev" Hello Danny, On 01/20/2015 10:53 AM, Danny Zhou wrote: > DPDK interrupt notification/handling mechanism is based on UIO with > below limitation: > 1) It is designed to handle LSC interrupt only with inefficient > suspended pthread wakeup procedure (e.g. UIO wakes up LSC interrupt > handling thread which then wakes up DPDK polling thread). In this way, > it introduces non-deterministic wakeup latency for DPDK polling thread > as well as packet latency if it is used to handle Rx interrupt. > 2) UIO only supports a single interrupt vector which has to been shared > by LSC interrupt and interrupts assigned to dedicated rx queues. > > This patchset includes below features: > 1) Enable one-shot rx queue interrupt in ixgbe PMD for PF as well as VF. > 2) Build on top of the VFIO mechanism instead of UIO, so it could support > up to 64 interrupt vectors for rx queue interrupts. > 3) Have 1 DPDK polling thread handle per Rx queue interrupt with a > dedicated VFIO eventfd, which eliminates non-deterministic pthread wakeup > latency in user space. > 4) Demonstrate interrupts control APIs and userspace NAIP-like > polling/interrupt switch algorithms in L3fwd-power example. In the patch 3/5: - the function eal_intr_process_rx_interrupts() systematically returns 0. It should be declared as "void" (and get rid of the return 0). - the function eal_intr_handle_rx_interrupts() loops again when epoll_wait() returns with errno == EINTR. It should also return in this case. - the function rte_eal_wait_rx_intr() should not invoke rte_panic() but instead return "-errno" upon system call failure. With these fixes: Acked-By: Ivan Boule -- Ivan Boule 6WIND Development Engineer