From: Ben Hutchings <bhutchings@solarflare.com>
To: David Miller <davem@davemloft.net>
Cc: therbert@google.com, alexander.h.duyck@intel.com, netdev@vger.kernel.org
Subject: Re: [RFC PATCH 0/3] Simplified 16 bit Toeplitz hash algorithm
Date: Mon, 03 Jan 2011 19:30:39 +0000 [thread overview]
Message-ID: <1294083039.3167.184.camel@localhost> (raw)
In-Reply-To: <20110103.110244.183045594.davem@davemloft.net>
On Mon, 2011-01-03 at 11:02 -0800, David Miller wrote:
> From: Tom Herbert <therbert@google.com>
> Date: Mon, 3 Jan 2011 10:47:20 -0800
>
> > I'm not sure why this would be needed. What is the a advantage in
> > making the TX and RX queues match?
>
> That's how their hardware based RFS essentially works.
>
> Instead of watching for "I/O system calls" like we do in software, the
> chip watches for which TX queue a flow ends up on and matches things
> up on the receive side with the same numbered RX queue to match.
ixgbe also implements IRQ affinity setting (or rather hinting) and TX
queue selection by CPU, the inverse of IRQ affinity setting. Together
with the hardware/firmware Flow Director feature, this should indeed
result in hardware RFS. (However, irqbalanced does not yet follow the
affinity hints AFAIK, so this requires some manual intervention. Maybe
the OOT driver is different?)
The proposed change to make TX queue selection hash-based seems to be a
step backwards.
Ben.
--
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.
next prev parent reply other threads:[~2011-01-03 19:30 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-18 1:00 [RFC PATCH 0/3] Simplified 16 bit Toeplitz hash algorithm Alexander Duyck
2010-12-18 1:00 ` [RFC PATCH 1/3] net: add simplified 16 bit Toeplitz hash function for transmit side hashing Alexander Duyck
2010-12-18 1:00 ` [RFC PATCH 2/3] ixgbe: example of how to update ixgbe to make use of in-kernel Toeplitz hash Alexander Duyck
2010-12-18 1:00 ` [RFC PATCH 3/3] igb: example of how to update igb to make use of in-kernel Toeplitz hashing Alexander Duyck
2010-12-18 5:09 ` David Miller
2010-12-18 6:53 ` Alexander Duyck
2010-12-18 6:59 ` David Miller
2011-01-03 18:47 ` [RFC PATCH 0/3] Simplified 16 bit Toeplitz hash algorithm Tom Herbert
2011-01-03 19:00 ` Alexander Duyck
2011-01-03 19:02 ` David Miller
2011-01-03 19:30 ` Ben Hutchings [this message]
2011-01-03 19:52 ` Alexander Duyck
2011-01-03 19:54 ` David Miller
2011-01-03 20:15 ` Ben Hutchings
2011-01-03 21:45 ` Alexander Duyck
2011-01-04 3:25 ` Tom Herbert
2011-01-04 15:43 ` Ben Hutchings
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