linux-kernel - Re: [PATCH] vt_buffer: drop console buffer copying optimisations

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Message-ID: <CA+55aFwNSKEpEGexJbcqpLuRJPLMA2pb9Pr61ikxidwAX3Hcyg@mail.gmail.com>
Date:	Thu, 29 Jan 2015 16:03:29 -0800
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	Dave Airlie <airlied@...hat.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	dri-devel@...ts.sf.net, Tomi Valkeinen <tomi.valkeinen@...com>
Subject: Re: [PATCH] vt_buffer: drop console buffer copying optimisations

On Thu, Jan 29, 2015 at 3:57 PM, Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
>
> I can take this through the tty tree, but can I put it in linux-next and
> wait for the 3.20 merge window to give people who might notice a
> slow-down a chance to object?

Yes. The problem only affects one (or a couple of) truly outrageously
bad graphics cards that are only used in servers (because they are
such crap that they wouldn't be acceptable anywhere else anyway), and
they have afaik never worked with 64-bit kernels, so it's not even a
regression.

So it's worth fixing because it's a real - albeit very rare - problem
(especially since the enhanched rep instruction model of memcpy could
easily be *worse* than the 16-bit-at-a-time manual version), but I
wouldn't consider it anywhere near high priority.

                         Linus
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