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From: Li Zefan <lizf@cn.fujitsu.com>
To: Stefani Seibold <stefani@seibold.net>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Arnd Bergmann <arnd@arndb.de>, Andi Kleen <andi@firstfloor.org>,
	Amerigo Wang <xiyou.wangcong@gmail.com>,
	Joe Perches <joe@perches.com>,
	Roger Quadros <quadros.roger@gmail.com>,
	Greg Kroah-Hartman <gregkh@suse.de>,
	Mauro Carvalho Chehab <mchehab@redhat.com>,
	Shargorodsky Atal <ext-atal.shargorodsky@nokia.com>
Subject: Re: [PATCH] new kfifo API v.08 (fixed)
Date: Mon, 21 Dec 2009 09:10:24 +0800	[thread overview]
Message-ID: <4B2ECB00.4060907@cn.fujitsu.com> (raw)
In-Reply-To: <1261303696.18283.22.camel@wall-e>

Stefani Seibold wrote:
> This is a complete rewrite of the new kfifo API, which is now really
> generic. The API is still stable. 
> 
> There are different types of a fifo which can not handled in C without a
> lot of overhead. So i decided to write the API as a set of macros, which 
> is the only way to do a kind of template meta programming without c++. 
> This macros handles the different types of fifos in a transparent way.
> 
> There are a lot of benefits:
> 
> - Compile time handling of the different fifo types
> - Performance (a save put or get of an integer does only generate 9 assembly
>   instructions on a x86) 
> - Type save
> - Cleaner interface, the additional kfifo_..._rec() functions are gone
> - Easier to use
> - Less error prone
> - Smaller footprint
> - Different types of fifos: it is now possible to define a int fifo or
>   any other type. See below for an example.
> - The size of the record field will be now detected at compile time
> - No need of creating a hidden variable, like in DEFINE_KFIFO
> 
> The API has not been change, but there are now real in place fifos
> where the data space is a part of the structure. There is no need for an
> extra indirection to the access the data and also no size field, because
> the size of the fifo can be determinate with sizeof. This kind of fifo
> does only need 8 bytes plus the fifo space.
> 
> The dynamic assigned or allocated fifos still needs 16 byte plus the 
> fifo space and does also creates more code.
> 
> Most of the macros code will be optimized away and does only generate a 
> function call.  Only the really the small ones generates inline code. The 
> overall size is half of the size of the previous implementation.
> 
> Additional you can now create fifos for any data type, not only the
> "unsigned char" byte streamed fifos.
> 
> There is also a new kfifo_put and kfifo_get function, to handle a single
> element in a fifo.
> 
> Here is a small example how to use it:
> 
> Example 1: an integer fifo
> 

Why don't you put those examples into samples/kfifo/ ?


      reply	other threads:[~2009-12-21  1:10 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-12-20 10:08 [PATCH] new kfifo API v.08 (fixed) Stefani Seibold
2009-12-21  1:10 ` Li Zefan [this message]

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