netdev - RE: [PATCH net-next 4/9] net: sctp: sctp_outq: consolidate chars into bitfield

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Date:	Wed, 17 Apr 2013 09:43:45 +0100
From:	"David Laight" <David.Laight@...LAB.COM>
To:	"Daniel Borkmann" <dborkman@...hat.com>, <davem@...emloft.net>
Cc:	<netdev@...r.kernel.org>, <linux-sctp@...r.kernel.org>
Subject: RE: [PATCH net-next 4/9] net: sctp: sctp_outq: consolidate chars into bitfield

>  	__u32 outstanding_bytes;
> 
> -	/* Are we doing fast-rtx on this queue */
> -	char fast_rtx;
> -
> -	/* Corked? */
> -	char cork;
> -
> -	/* Is this structure empty?  */
> -	char empty;
> +	__u8 fast_rtx:1,	/* Are we doing fast-rtx on this queue */
> +	     cork:1,		/* Corked? */
> +	     empty:1;		/* Is this structure empty?  */
>  };

Use of bitfields just makes the code slower.
The only real excuse for using them is to reduce the size
of a structure that is allocated a lot.

In the above you are just increasing the padding from
1 byte to 3 bytes.

	David



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