From: Marc Zyngier <marc.zyngier@arm.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>
Subject: Re: [RFC PATCH] arm64: KVM: remove fpsimd save/restore from the world switch
Date: Fri, 10 Apr 2015 11:08:38 +0100 [thread overview]
Message-ID: <5527A126.6080202@arm.com> (raw)
In-Reply-To: <CAFEAcA8J-kDHjkg9uFbHHAEu=zSSv+CB1Vmy1JBh==SmeiWL1Q@mail.gmail.com>
On 10/04/15 11:01, Peter Maydell wrote:
> On 10 April 2015 at 10:11, Marc Zyngier <marc.zyngier@arm.com> wrote:
>> I did some experimentations on arm64 a long while ago (see the
>> kvm-arm64/lazy-fp branch in my tree), and it wasn't that great,
>> apparently because aarch64 userspace tends to be much more FP happy than
>> aarch32, but I'm not completely sure about it.
>
> Was that with the buggy version of the toolchain that had
> incorrect costs and so was much more inclined to spill
> integer values into the FPU than it should have been?
> It might be worth retesting with a freshly compiled
> userspace some day...
It definitely was with a very old toolchain and an even older userspace.
I'll respin the branch when I get some thime.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2015-04-10 10:08 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-09 16:53 [RFC PATCH] arm64: KVM: remove fpsimd save/restore from the world switch Marc Zyngier
2015-04-10 8:41 ` Paolo Bonzini
2015-04-10 9:11 ` Marc Zyngier
2015-04-10 9:13 ` Paolo Bonzini
2015-04-10 9:40 ` Marc Zyngier
2015-04-10 10:01 ` Peter Maydell
2015-04-10 10:08 ` Marc Zyngier [this message]
2015-04-10 10:20 ` Catalin Marinas
2015-04-10 9:12 ` Christoffer Dall
2015-04-10 9:36 ` Marc Zyngier
2015-04-13 12:57 ` Christoffer Dall
2015-04-13 14:12 ` Marc Zyngier
2015-04-13 14:26 ` Christoffer Dall
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