linux-kernel - Re: [PATCH 1/2] kfifo: round up the fifo size power of 2

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Message-ID: <1351258786.10060.5.camel@wall-e>
Date:	Fri, 26 Oct 2012 15:39:46 +0200
From:	Stefani Seibold <stefani@...bold.net>
To:	Yuanhan Liu <yuanhan.liu@...ux.intel.com>
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 1/2] kfifo: round up the fifo size power of 2

Am Freitag, den 26.10.2012, 20:33 +0800 schrieb Yuanhan Liu:
> On Fri, Oct 26, 2012 at 11:30:27AM +0200, Stefani Seibold wrote:
> > Am Freitag, den 26.10.2012, 15:56 +0800 schrieb Yuanhan Liu:
> > > Say, if we want to allocate a filo with size of 6 bytes, it would be safer
> > > to allocate 8 bytes instead of 4 bytes.
> > > ----
> > > I know it works with rounddown_pow_of_two as well, since size is maintained
> > > in the kfifo internal part. But, I'm quite curious why Stefani chose
> > > rounddown_pow_of_two. To reduce memory?
> > > 
> > 
> > Yes, exactly, if a user do the wrong thing, than the user will get also
> > a wrong result, and did not waste memory.
> 
> But, isn't it better to 'correct' it? ;-)

Both is wrong. This depends on the view. For me it is better to get less
and don't wast space. For example: requesting 1025 will yield in your
case to a fifo which 2048 elements, which requires double of the memory
as expected.

> 
> > 
> > But anyway, if the majority like this patch it is okay for me.
> 
> Sorry, do you mean you are OK with this patch?
> 

I depends not on me, ask for a democratic decisions.

Greetings,
Stefani


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