Re: [patch] context-switching overhead in X, ioport(), 2.6.8.1

From: Andi Kleen
Date: Sun Aug 22 2004 - 09:26:47 EST


> Xorg and XFree assume the kernel will have intelligent limits. When the
> range went up the EnableIO code in turn switched to ioperm.

Which was the wrong thing to do since it is slower.

>
> The actual code is:
>
> if (ioperm(0, 1024, 1) || iopl(3))
> FatalError("xf86EnableIOPorts: Failed to set IOPL for
> I/O\n")
>
> (os-support/linux/lnx_video.c:xf86EnableIO)
>
> Flip those around and rebuild.

It would be better to do that in the official release.

-Andi
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