[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH] [RFC] Variable video ram size option
From: |
Gerd Hoffmann |
Subject: |
Re: [Qemu-devel] [PATCH] [RFC] Variable video ram size option |
Date: |
Thu, 15 Jan 2009 22:41:59 +0100 |
User-agent: |
Thunderbird 2.0.0.19 (X11/20090105) |
Jamie Lokier wrote:
> Gerd Hoffmann wrote:
>> Jamie Lokier wrote:
>>> I don't know why "ypan" is off by default;
>> Performance. When reaching the end of video memory ypan does a memcpy
>> on the framebuffer. ywrap doesn't need the memcpy, but doesn't work on
>> all hardware. The memcpy is painful slow because framebuffer *read*
>> access isn't something gfx cards are optimized for.
>
> Why read the framebuffer at all?
Has been quite a while that I looked closer at the fb code and followed
fb development.
IIRC it has to do something with the scrollback (Shift-PgUp/Down)
implementation: The video memory is used as scrollback buffer. Thus
some information is kept in the video memory *only*.
> My experience with real hardware is it makes scrolling noticably faster.
Well, maybe it has been changed then. I remember having seen some
discussion on changing the scrollback implementation to not depend on
video memory, which could have fixed this too.
cheers,
Gerd
- Re: [Qemu-devel] [PATCH] [RFC] Variable video ram size option, (continued)
- Re: [Qemu-devel] [PATCH] [RFC] Variable video ram size option, Trolle Selander, 2009/01/12
- Re: [Qemu-devel] [PATCH] [RFC] Variable video ram size option, Paul Brook, 2009/01/14
- Re: [Qemu-devel] [PATCH] [RFC] Variable video ram size option, Trolle Selander, 2009/01/14
- Re: [Qemu-devel] [PATCH] [RFC] Variable video ram size option, Paul Brook, 2009/01/14
- Re: [Qemu-devel] [PATCH] [RFC] Variable video ram size option, Trolle Selander, 2009/01/14
- Re: [Qemu-devel] [PATCH] [RFC] Variable video ram size option, Jamie Lokier, 2009/01/15
- Re: [Qemu-devel] [PATCH] [RFC] Variable video ram size option, Rene Rebe, 2009/01/15
- Re: [Qemu-devel] [PATCH] [RFC] Variable video ram size option, Jamie Lokier, 2009/01/15
- Re: [Qemu-devel] [PATCH] [RFC] Variable video ram size option, Gerd Hoffmann, 2009/01/15
- Re: [Qemu-devel] [PATCH] [RFC] Variable video ram size option, Jamie Lokier, 2009/01/15
- Re: [Qemu-devel] [PATCH] [RFC] Variable video ram size option,
Gerd Hoffmann <=