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Re: Tags are dead alias Milo is dead part II

To: ralf@uni-koblenz.de
Subject: Re: Tags are dead alias Milo is dead part II
From: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Date: Thu, 8 Oct 1998 21:58:34 +0200
Cc: linux-mips@fnet.fr, linux-mips@vger.rutgers.edu, linux@cthulhu.engr.sgi.com
In-reply-to: <19981008170335.H4058@uni-koblenz.de>; from ralf@uni-koblenz.de on Thu, Oct 08, 1998 at 05:03:35PM +0200
References: <19981007002547.44731@alpha.franken.de> <19981008170335.H4058@uni-koblenz.de>
Sender: owner-linux@cthulhu.engr.sgi.com
On Thu, Oct 08, 1998 at 05:03:35PM +0200, ralf@uni-koblenz.de wrote:
> Applied to the G364 drivers (which as of now is still MIPS specific anyway)
> this means that we'll avoid TLB trashing in the case of scrolling and have
> the full TLB available for userland.

I don't believe this will buy us anything. When we add a temporary TLB we need
do clear one TLB, which might be used by the userland. So we end up loading
our wired entry, killing it, and later the user process has to reload the 
TLB again. This way we force TLB trashing, with one wired entry more we
_might_ get a little bit more TLB trashing.

As you might know, I'm using three wired entries for the Magnum, and I don't 
think doing the same trick for the other entries is a real good idea. When 
we make them temporary, we have to mess with TLBs on every interrupt.

Thomas.

-- 
   This device has completely bogus header. Compaq scores again :-|
It's a host bridge, but it should be called ghost bridge instead ;^)
                                        [Martin `MJ' Mares on linux-kernel]

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