From: Paolo Bonzini <pbonzini@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH] kvm: x86: disable KVM_FAST_MMIO_BUS
Date: Wed, 16 Aug 2017 10:17:10 -0400 (EDT) [thread overview]
Message-ID: <1530586086.975916.1502893030374.JavaMail.zimbra@redhat.com> (raw)
In-Reply-To: <20170816170329-mutt-send-email-mst@kernel.org>
> We actually know what to expect (a write) so we could maybe
> optimize this some more with a dedicated function just for this.
We don't know the addressing mode, the size or the source (immediate
vs. register), so no.
KVM is already doing a single translation and read no matter how long
the instruction (unless it cross page boundaries).
Paolo
> >
> > However, the eventfd is written before decoding, while full emulation
> > would write it after. So while VCPU thread latency is worse compared to
> > skip_emulated_instruction, latency to the iothread remains small.
> >
> > Paolo
>
next prev parent reply other threads:[~2017-08-16 14:17 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-16 11:22 [PATCH] kvm: x86: disable KVM_FAST_MMIO_BUS Paolo Bonzini
2017-08-16 12:07 ` Radim Krčmář
2017-08-16 13:37 ` Paolo Bonzini
2017-08-16 14:06 ` Michael S. Tsirkin
2017-08-16 14:17 ` Paolo Bonzini [this message]
2017-08-17 8:15 ` David Hildenbrand
2017-08-16 12:58 ` Michael S. Tsirkin
2017-08-16 13:05 ` Paolo Bonzini
2017-08-16 13:16 ` Michael S. Tsirkin
2017-08-16 13:30 ` Paolo Bonzini
2017-08-16 14:03 ` Michael S. Tsirkin
2017-08-16 16:50 ` Michael S. Tsirkin
2017-08-16 17:19 ` Paolo Bonzini
2017-08-16 19:03 ` Radim Krčmář
2017-08-16 19:59 ` Michael S. Tsirkin
2017-08-16 21:25 ` Paolo Bonzini
2017-08-16 22:31 ` Michael S. Tsirkin
2017-08-17 9:00 ` Paolo Bonzini
2017-08-17 12:14 ` Paolo Bonzini
2017-08-17 13:23 ` Radim Krčmář
2017-08-17 15:15 ` Michael S. Tsirkin
2017-08-17 13:51 ` Radim Krčmář
2017-08-17 15:27 ` Michael S. Tsirkin
2017-08-16 19:47 ` Michael S. Tsirkin
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