From: Rick Jones <rick.jones2@hp.com>
To: Qin Chuanyu <qinchuanyu@huawei.com>, netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Subject: Re: What's the concern about setting irq thread's policy as SCHED_FIFO
Date: Wed, 03 Dec 2014 08:51:30 -0800 [thread overview]
Message-ID: <547F3F92.2050501@hp.com> (raw)
In-Reply-To: <547EC4A3.6060408@huawei.com>
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 <netperfCPU>,<netserverCPU> ...
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?
>
> --
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next prev parent reply other threads:[~2014-12-03 16:51 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-03 8:06 What's the concern about setting irq thread's policy as SCHED_FIFO Qin Chuanyu
2014-12-03 16:51 ` Rick Jones [this message]
2014-12-04 3:12 ` Qin Chuanyu
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