From mboxrd@z Thu Jan  1 00:00:00 1970
From: Pankaj Gupta <pagupta@redhat.com>
Subject: Re: [PATCH v2 net-next 3/3] tuntap: reduce the size of tun_struct
 by using flex array.
Date: Wed, 26 Nov 2014 02:40:14 -0500 (EST)
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References: <1416854044-10124-1-git-send-email-pagupta@redhat.com> <20141125.132717.122094133335261929.davem@davemloft.net>
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Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
	jasowang@redhat.com, dgibson@redhat.com, vfalico@gmail.com,
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	stephen@networkplumber.org, jiri@resnulli.us,
	sergei shtylyov <sergei.shtylyov@cogentembedded.com>,
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To: David Miller <davem@davemloft.net>
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> 
> From: Pankaj Gupta <pagupta@redhat.com>
> Date: Tue, 25 Nov 2014 00:04:04 +0530
> 
> > This patch switches to flex array to implement the flow caches, it brings
> > several advantages:
> > 
> > - Reduce the size of the tun_struct structure, which allows us to increase
> > the
> >   upper limit of queues in future.
> > - Avoid higher order memory allocation. It will be useful when switching to
> >   pure hashing in flow cache which may demand a larger size array in
> >   future.
> > 
> > After this patch, the size of tun_struct on x86_64 reduced from 8512 to
> > 328
> > 
> > Signed-off-by: Jason Wang <jasowang@redhat.com>
> > Signed-off-by: Pankaj Gupta <pagupta@redhat.com>
> > Reviewed-by: David Gibson <dgibson@redhat.com>
> 
> I see no reason to use flex arrays for this, you are preallocaing the
> memory so if anything flex array is adding an unnecessary level of
> redirection for every access in return for no real gains.
> 
> Just allocate the thing normally using kzalloc() or whatever.

I agree. Will do the changes and submit v3.
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