netdev - Re: [PATCH] ifb: add multi-queue support

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: <20091113153229.408c889f@nehalam>
Date:	Fri, 13 Nov 2009 15:32:29 -0800
From:	Stephen Hemminger <shemminger@...tta.com>
To:	Changli Gao <xiaosuo@...il.com>
Cc:	Jarek Poplawski <jarkao2@...il.com>,
	Eric Dumazet <eric.dumazet@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Patrick McHardy <kaber@...sh.net>,
	Tom Herbert <therbert@...gle.com>, netdev@...r.kernel.org
Subject: Re: [PATCH] ifb: add multi-queue support

On Sat, 14 Nov 2009 07:28:42 +0800
Changli Gao <xiaosuo@...il.com> wrote:

> On Sat, Nov 14, 2009 at 12:15 AM, Stephen Hemminger
> <shemminger@...tta.com> wrote:
> > On Fri, 13 Nov 2009 17:38:56 +0800
> > Changli Gao <xiaosuo@...il.com> wrote:
> >>
> >> Oh, :) . I know more than one companies use kernel threads to forward
> >> packets, and there isn't explicit extra overhead at all. And as you
> >> know, as throughput increases, NAPI will bind the NIC to a CPU, and
> >> softirqd will be waked up to do the work, which should be done in
> >> SoftIRQ context. At that time, there isn't any difference between my
> >> approach and the current kernel's.
> >>
> > Why not make IFB a NAPI device. This would get rid of the extra soft-irq
> > round trip from going through netif_rx().  It would also behave like
> > regular multi-queue recieive device, and eliminate need for seperate
> > tasklets or threads.
> >
> 
> It needs to send remote SoftIRQ, as Receiving Packet Steering, and we
> must support a extra interface to map load to CPUs.
> 

But it still could use NAPI to avoid causing excess packet overhead.
The softirq could be equivalent of hardirq in network device.

-- 
--
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