netdev - Re: [PATCH] net core: optimize netdev_create

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Message-ID: <20130316011942.GC5531@weiyang.vnet.ibm.com>
Date:	Sat, 16 Mar 2013 09:19:42 +0800
From:	Wei Yang <weiyang@...ux.vnet.ibm.com>
To:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH] net core: optimize netdev_create_hash()

[resend for syntax error in Message-ID]

David, 

Thanks for pointing out the error, it really helps.

I guess last mail is still blocked by the mail server, so I resend it.
Hope it works now.

On Sat, Mar 16, 2013 at 08:00:51AM +0800, Wei Yang wrote:
On Fri, Mar 15, 2013 at 05:39:30PM -0400, David Miller wrote:
>From: Wei Yang <weiyang@...ux.vnet.ibm.com>
>Date: Sat, 16 Mar 2013 00:32:11 +0800
>
>> netdev_create_hash() is divded into two steps:
>> 1. allocate space for hash_head
>> 2. initialize hash_head->first to NULL for each hash_head
>> 
>> This patch merge the two steps into one step.
>> 
>> When allocating the space for hash_head, it will use kzalloc() instead of
>> kmalloc(). Then hash_head->first is set to NULL during the allocation step,
>> which means it is not necessary to call INIT_HLIST_HEAD() for each hash_head.
>> 
>> This will:
>> 1. reduce the code size
>> 2. reduce the run time of iteration on initializing hash_head array
>
>Please do not ever post changes like this.
>
>This makes assumtions about the list head implementation that
>we should not make.  If someone adds a debugging facility that
>causes lists to be initialized differently, it will be broken
>for this hash table now.

Yes, this is based on the assumtion. 
And agree, this will break the behavior.

>
>The reason the abstractions exist is so that people do not
>do things like you are trying to do.
>
>If you want to add an interface in the generic list facilities which
>performs this simplifcation, fine.  Implement it and post such a
>suggestion to linux-kernel, and then once such a facility is present
>in Linus's tree we can start using it in the networkng code.

Thanks for your suggestion and kindness.

-- 
Richard Yang
Help you, Help me

-- 
Richard Yang
Help you, Help me

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