Subject: Re: [linux-audio-user] Re: [a-users] Re: [a-devel] File system and Voluntary Kernel Preemption
From: Lee Revell (rlrevell_AT_joe-job.com)
Date: Fri Jul 16 2004 - 22:24:23 EEST
On Fri, 2004-07-16 at 04:33, Malcolm Baldridge wrote:
> > Some of these fixes were to
> > extremely important areas (get_user_pages, a fix for
> > framebuffer-scrolling issue, and more).
> It goes against common sense (to anyone with kernel knowledge) to use the
> console framebuffer anyway.
> The duration of kernel locks and the CPU expense of blowing bitmaps around
> like that are shocking.
> Seriously. Use text-mode consoles, or a native AGP-driver a la nvidia, ati,
> or whatever. But using a "stupid" framebuffer driver is asking for hardcore
> latency blow-outs.
I am using text-mode consoles, and switching back and forth between
those and X using ctrl-alt-F[1-7]. I sent Andrew Morton some XRUN
traces and he said one of them was caused by framebuffer scolling inside
lock_kernel(), and the fix was to remove (un)lock_kernel() from
do_tty_write(). This particular fix may not be in -mm1, because he
seemed to think it would cause problems (display corruption, etc). It
has not caused any problems for me.
Maybe I am confused about the 'framebuffer' vs. a text-mode console, I
thought they were the same. Anyway, the point is, switching from X to a
text-mode console and back caused XRUNS before, and now it doesn't.
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