Re: [patch] lazy TSS's I/O bitmap copy ...

[Davide Libenzi]

On Tue, 24 Aug 2004, Arjan van de Ven wrote:

> On Mon, 2004-08-23 at 23:23, Davide Libenzi wrote:
> > The following patch implements a lazy I/O bitmap copy for the i386 
> > architecture. With I/O bitmaps now reaching considerable sizes, if the 
> > switched task does not perform any I/O operation, we can save the copy 
> > altogether. In my box X is working fine with the following patch, even if 
> > more test would be required.
> 
> the thing is that X will not hit your fault path, since it runs with
> iopl() called... your patch is a nice optimisation for X as a result,
> however as test, X is almost worthless ;(

Arjan, using FC1 here and X definitely hits the GPF path. A few crashes 
when doing The Wrong Thing confirmed it yesterday :-) Also, according to 
the snippet Alan posted, X does iopl() on fallback of failing ioperm() IIRC.



- Davide

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