nanogui: Speed Issues on a slow CPU
Subject:
Re: [nanogui] Speed Issues on a slow CPU
From:
Amadeus ####@####.####
Date:
4 Oct 2007 18:20:49 +0100
Message-Id: <200710041920.42467.amadeus@iksw-muees.de>
Hello Alan,
On Mittwoch, 3. Oktober 2007, Alan Cox wrote:
> > The speed of a burst read is 120ns for 16 bit. Not much...
> > I have not investigated into running apps in thumb mode.
>
> That may help, also putting the blitter functions into assembler and
> using the ability to lock them into cache. This is where stuff like
> gprof timing can reveal the true hotspots.
I have put the whole nano-X server into internal ram. This has helped,
but speed is still not acceptable. I will show if I can blitt in
assembler...
> Thats pretty tight. I'd assumed you were able to use the full 32MB as
> well.
Oops.. missunderstanding. I am able to use the full 32 MB as well.
> > There is one SERIOUS problem in this area I have not found a
> > solution for: as soon as FAT16 with 32 KByte cluster size is used
> > (needed for the common 2 GByte SD cards), DSLINUX has problems to
> > handle them. There are data aborts while directory traversal. I
> > have not heard from any other embedded system having this problem,
> > and it looks rather strange to me.
>
> I've not seen similar reports at all, but I don't know how many
> people are using FAT16 on such devices on a PC in Linux.
I can open and use these cards on my desktop PC without problems...
regards
Amadeus
--
We're back to the times when men were men
and wrote their own device drivers.
(Linus Torvalds)
