From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rick Jones Subject: Re: What's the concern about setting irq thread's policy as SCHED_FIFO Date: Wed, 03 Dec 2014 08:51:30 -0800 Message-ID: <547F3F92.2050501@hp.com> References: <547EC4A3.6060408@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org To: Qin Chuanyu , netdev@vger.kernel.org Return-path: In-Reply-To: <547EC4A3.6060408@huawei.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 12/03/2014 12:06 AM, Qin Chuanyu wrote: > I am doing network performance test under suse11sp3 and intel 82599 nic, > Becasuse the softirq is out of schedule policy's control, so netserver > thread couldn't always get 100% cpu usage, then packet dropped in kernel > udp socket's receive queue. > > In order to get a stable result, I did some patch in ixgbe driver and > then use irq_thread instead of softirq to handle rx. > It seems work well, but irq_thread's SCHED_FIFO schedule policy cause > that when the cpu is limited, netserver couldn't work at all. I cannot speak to any scheduling issues/questions, but can ask if you tried binding netserver to a CPU other than the one servicing the interrupts via the -T option on the netperf command line: netperf -T , ... http://www.netperf.org/svn/netperf2/trunk/doc/netperf.html#index-g_t_002dT_002c-Global-41 happy benchnmarking, rick jones > > So I change the irq_thread's schedule policy from SCHED_FIFO to > SCHED_NORMAL, then the irq_thread could share the cpu usage with > netserver thread. > > the question is: > What's the concrete reason about setting irq thread's policy as SCHED_FIFO? > Except the priority affecting the cpu usage, any function would be > broken if irq thread change to SCHED_NORMAL? > > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html