Re: Huge console switching lags

[Paul Mundt <pmundt@mvista.com>]

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On Wed, Oct 03, 2001 at 09:58:30AM -0700, James Simmons wrote:
> > Well, there are indeed a few improvements to get with machine specific
> > optimisations on unaccelerated framebuffer.
> [snip]...
> 
> Neat trick. Please note also that no read operations to the framebuffer
> are done by the fbcon layer. Such reads should be to the shadow buffers
> (vc_screenbuffer) instead. Reading the framebuffer is a userland operation
> and as such you really only tricks for reading in userland. 
> 
And while we're on the subject of architecture specific optimizations for
unaccelerated framebuffers (or framebuffers in general for that matter),
on SH4 you can remap the video memory area through a store queue and perform
all writes through the remapped store queue area (there are two store queues,
each are 32bytes, and are flushed to the memory they were mapped to on a
prefetch instruction). This allows for very high speed writes to external
memory, as it was designed for.

Regards,

-- 
Paul Mundt <pmundt@mvista.com>
MontaVista Software, Inc.


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