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Date: Mon, 14 Nov 2011 16:08:14 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Ilya Zykov <ilya@ilyx.ru>
Cc: Jiri Slaby <jslaby@suse.cz>, Alan Cox <alan@linux.intel.com>,
        linux-kernel@vger.kernel.org, Greg Kroah-Hartman <gregkh@suse.de>,
        Jiri Slaby <jirislaby@gmail.com>
Subject: Re: [PATCH v3 2/2] TTY: tty flip buffer optimisation.
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> 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.

The buffer cycling was added because it speeds up some cases (as you
found), and because its needed for high speed serial on some very low end
devices. From your benchmarks it's also speeding up pty/tty so it's
clearly relevant.

Alan