netdev - Re: [PATCH] dev: use name hash for dev_seq

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Date:	Sat, 8 Oct 2011 10:22:26 +0300
From:	Mihai Maruseac <mihai.maruseac@...il.com>
To:	Stephen Hemminger <shemminger@...tta.com>
Cc:	davem@...emloft.net, eric.dumazet@...il.com,
	mirq-linux@...e.qmqm.pl, therbert@...gle.com, jpirko@...hat.com,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	dbaluta@...acom.com, Mihai Maruseac <mmaruseac@...acom.com>
Subject: Re: [PATCH] dev: use name hash for dev_seq_ops.

On Fri, Oct 7, 2011 at 7:24 PM, Stephen Hemminger <shemminger@...tta.com> wrote:
> On Fri,  7 Oct 2011 18:20:49 +0300
> Mihai Maruseac <mihai.maruseac@...il.com> wrote:
>
>> Instead of using the dev->next chain and trying to resync at each call to
>> dev_seq_start, use this hash and store bucket number and bucket offset in
>> seq->private field.
>>
>> Tests revealed the following results for ifconfig > /dev/null
>>       * 1000 interfaces:
>>               * 0.114s without patch
>>               * 0.020s with patch
>>       * 3000 interfaces:
>>               * 0.489s without patch
>>               * 0.048s with patch
>>       * 5000 interfaces:
>>               * 1.363s without patch
>>               * 0.131s with patch
>>
>> As one can notice the improvement is of 1 order of magnitude.
>
> Good idea,
> This will change the ordering of entries in /proc which may upset
> some program, not a critical flaw but worth noting.
>
> Rather than recording the bucket and offset of last entry, another
> alternative would be to just record the ifindex.
>
> Also ifconfig is considered deprecated and replaced by ip commands
> for general use.
>

Thanks,
This is a patch from a series of improvements to both the ifconfig and
ip commands. The ip part will come later, after being properly
implemented and tested.

-- 
Mihai
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