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Date:      Thu, 25 Oct 2001 15:19:35 -0700
From:      Luigi Rizzo <rizzo@aciri.org>
To:        Doug Rabson <dfr@nlsystems.com>
Cc:        John Baldwin <jhb@FreeBSD.org>, Jonathan Lemon <jlemon@FreeBSD.org>, cvs-all@FreeBSD.org, cvs-committers@FreeBSD.org
Subject:   Re: cvs commit: src/sys/dev/fxp if_fxp.c
Message-ID:  <20011025151935.G57392@iguana.aciri.org>
In-Reply-To: <20011025231245.K549-100000@salmon.nlsystems.com>
References:  <20011025143748.C57392@iguana.aciri.org> <20011025231245.K549-100000@salmon.nlsystems.com>

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> > does it mean that integer multiply in the kernel is bad on the ia64 :)
> 
> Not really - its reasonably quick. They just didn't bother to add any
> integer multipliers when there were two perfectly good floating point
> units going idle. Moving integers in and out of float registers is quick
> and easy so it actually makes sense. Divides are done with floating point
> too.

the point for not having FP in the kernel is not speed, but rather
the fact that you do not have to save those registers in a context
switch. This could just be an artifact of ancient times where FPU's
were separate units...

So, i guess the FP registers are saved in the IA64 context switch routines ?

	luigi

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