RE: [PATCH v2 0/7] KVM: arm/arm64: gsi routing support

From: Pavel Fedin <p.fedin@samsung.com>
To: 'Eric Auger' <eric.auger@linaro.org>,
	'Andre Przywara' <andre.przywara@arm.com>,
	linux-arm-kernel@lists.infradead.org
Cc: eric.auger@st.com, kvm@vger.kernel.org,
	'Marc Zyngier' <Marc.Zyngier@arm.com>,
	pbonzini@redhat.com, kvmarm@lists.cs.columbia.edu
Subject: RE: [PATCH v2 0/7] KVM: arm/arm64: gsi routing support
Date: Thu, 09 Jul 2015 21:08:36 +0300	[thread overview]
Message-ID: <028401d0ba72$4736dbc0$d5a49340$@samsung.com> (raw)
In-Reply-To: <559EAB3D.2080205@linaro.org>

> Well personally I prefer the type thing and I don't see much difference
> at userspace level anyway. But I am not this kind of hyperspace
> architect guy. So, since there is no consensus here, I would say let's
> wait for formal reviews of our maintainers and I will align.

 Hah, okay... Don't take it for too much. Anyway your word weighs much more than my one...

> hope this eventually works with
> ITS ;-)

 You know... There are actually problems with irqfd. However i'm not sure whether they are result of
some bug or of poorly made vGIC CPU interface software emulation. I don't have hardware with working
vGICv3 here. With GICv2m everything is fine, but code path is quite different, and LPI != SPI.
 This is further overcomplicated by the fact that as soon as i start up the profiler, the problem
goes away. Looks like increased number of context switches have impact.
 Actually, the problem is very poor vhost-net throughput, which jumps up when i start the profiler
and goes back down when i stop it. Just to note...
 I'm off since now for a small vacation, will be back on monday or tuesday. See you guys!

Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia