netdev - Re: [RFC PATCH 3/3] igb: example of how to update igb to make use of in-kernel Toeplitz hashing

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Message-ID: <AANLkTimuXo+ZJKmz4U38mLd8x-KymJ0BQxTTjDT2bjgy@mail.gmail.com>
Date:	Fri, 17 Dec 2010 22:53:24 -0800
From:	Alexander Duyck <alexander.duyck@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	alexander.h.duyck@...el.com, netdev@...r.kernel.org
Subject: Re: [RFC PATCH 3/3] igb: example of how to update igb to make use of
 in-kernel Toeplitz hashing

On Fri, Dec 17, 2010 at 9:09 PM, David Miller <davem@...emloft.net> wrote:
> From: Alexander Duyck <alexander.h.duyck@...el.com>
> Date: Fri, 17 Dec 2010 17:00:48 -0800
>
>> @@ -1691,6 +1692,7 @@ static const struct net_device_ops igb_netdev_ops = {
>>       .ndo_open               = igb_open,
>>       .ndo_stop               = igb_close,
>>       .ndo_start_xmit         = igb_xmit_frame_adv,
>> +     .ndo_select_queue       = toeplitz_select_queue,
>>       .ndo_get_stats64        = igb_get_stats64,
>>       .ndo_set_rx_mode        = igb_set_rx_mode,
>>       .ndo_set_multicast_list = igb_set_rx_mode,
>
> Adding a NETIF_F_TX_TOEPLITZ flag that skb_tx_hash() keys off of would
> be a lot simpler

Thats probably true.  I hadn't put much thought into it at the time.

> We want less overriding of ->ndo_select_queue(), not more, and this case
> is definitely gratuitous.

I kind of figured that was the approach was flawed.  As I said in the
cover page, this is a somewhat hastily thrown together set of patches
to demonstrate a proof of concept.  To me this appeared to be the
quickest way to come up with the means to alter the queue selection.
The main piece I am interested in is any input on the first patch that
added the Toeplitz hash functionality.  Specifically would a 16 bit
key/hash work for queue selection or would there be cases where we
need a 32 bit key/hash result?

Thanks,

Alex
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