Re: [PATCH] fbdefio: add set_page_dirty handler to deferred IO FB

From: Jeremy Fitzhardinge
Date: Wed Aug 20 2008 - 14:47:47 EST


Jaya Kumar wrote:
> I hope I have understood your question. You are right that PG_dirty
> isn't used directly in defio. The defio portion does use each
> page_mkwrite callback to build a list of the pages of the framebuffer
> that were written to and then passes that list to pvfb (in this case).
> pvfb then optimizes writeback by interpreting that list according to
> its framebuffer and sending it to its actual destination. I think
> Markus's code in xenfb_deferred_io() and xenfb_send* is doing the
> latter.
>

The original Xen-specific implementation of this did use PG_dirty, which
has the nice property of using the hardware feature without invoking any
pagefaults. It would be nice if defio could be extended to allow this
on platforms where it makes sense.

J
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