linux-kernel - Re: [PATCH v3 2/2] TTY: tty flip buffer optimisation.

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Date:	Mon, 14 Nov 2011 19:47:02 +0400
From:	Ilya Zykov <ilya@...x.ru>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
CC:	Jiri Slaby <jslaby@...e.cz>, Alan Cox <alan@...ux.intel.com>,
	linux-kernel@...r.kernel.org, Greg Kroah-Hartman <gregkh@...e.de>,
	Jiri Slaby <jirislaby@...il.com>
Subject: Re: [PATCH v3 2/2] TTY: tty flip buffer optimisation.

Alan Cox wrote:

>> Hi, the results are indeed nice. However is there any *real* load other
>> than this tailor-made microbenchmark where the added code complexity is
>> worth it?
> 
> I'm wondering if we need the complexity in the first place. Certainly 256
> does seem a bit small for pty/tty traffic. A 'real world' benchmark would
> be an ls -lR / on a machine with a fast graphics card or in console mode
> 
> ie
> 
> ls -lR /		# prime cache
> time ls -lR /
> 
> and there are cases where people do a lot of traffic over a pty like this
> so I don't think it's entirely fake.
> 
> I don't like the complexity but we could certainly go from using 256 byte
> buffers to "tty->buf.bufsize" and make it configurable without
> that complexity.
> 
> Alan
> 


For avoid complexity we need remove free buffer at all.
And use kmalloc()-kfree() for every chunk. Don't need tty_buffer_find().
It will be fast and easy.
Ilya.

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