netdev - Re: What's the concern about setting irq thread's policy as SCHED

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <547F3F92.2050501@hp.com>
Date:	Wed, 03 Dec 2014 08:51:30 -0800
From:	Rick Jones <rick.jones2@...com>
To:	Qin Chuanyu <qinchuanyu@...wei.com>, netdev@...r.kernel.org
CC:	linux-kernel@...r.kernel.org
Subject: Re: What's the concern about setting irq thread's policy as SCHED_FIFO

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?
>
> --
> To unsubscribe from this list: send the line "unsubscribe netdev" in
> the body of a message to majordomo@...r.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html