From: David Gibson <david@gibson.dropbear.id.au>
To: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Cc: Richard Henderson <richard.henderson@linaro.org>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] tcg/ppc: Add vector opcodes
Date: Mon, 25 Feb 2019 10:31:42 +1100 [thread overview]
Message-ID: <20190224233142.GC7668@umbus.fritz.box> (raw)
In-Reply-To: <a46631f2-fc78-2f06-09f0-25b2563af52d@ilande.co.uk>
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On Fri, Feb 22, 2019 at 05:13:37PM +0000, Mark Cave-Ayland wrote:
> On 22/02/2019 05:59, Richard Henderson wrote:
>
> > This requires VSX, not just Altivec, so Power7 or later.
> >
> > Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> > ---
> >
> > At present there are no tunables that can avoid the 64-bit element
> > load/store requirement. As with requiring AVX1 for x86 hosts, I'm
> > not sure it's worth inventing such a tunable for pre-power7 hosts.
> >
> > Tested vs aarch64 risu test cases. It's probably worth testing
> > this vs Mark's target/ppc conversion.
>
> Oooh this looks really exciting! However... I only have a G4 Mac Mini around that I
> use for testing which is Altivec-only :( Is it much work to support
> non-VSX hosts?
I have access to POWER8 and POWER9 machines, but I haven't worked with
RISU before. If you can give me a straightforward recipe I can try
running the tests.
>
> This leads me to a related point that came up when Howard and I were testing the PPC
> vector patches - how do we know at runtime which optimisations were being used, e.g.
> what is the value of have_avx2 on a particular CPU running QEMU?
>
> Under Linux this isn't too bad since you can just do "cat /proc/cpuinfo | grep avx2"
> but it becomes more tricky when getting bug reports from Windows users who aren't
> particularly technical...
>
>
> ATB,
>
> Mark.
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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next prev parent reply other threads:[~2019-02-24 23:37 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-22 5:59 [Qemu-devel] [PATCH] tcg/ppc: Add vector opcodes Richard Henderson
2019-02-22 17:13 ` Mark Cave-Ayland
2019-02-22 20:20 ` Richard Henderson
2019-02-24 23:31 ` David Gibson [this message]
2019-02-28 0:47 ` Richard Henderson
2019-02-28 4:01 ` David Gibson
2019-02-28 5:11 ` Richard Henderson
2019-02-27 15:45 ` no-reply
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