From: Paul Mackerras <paulus@ozlabs.org>
To: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org,
kvm-ppc@vger.kernel.org
Subject: Re: [PATCH] KVM: PPC: Book3S HV: Optimise mmio emulation for devices on FAST_MMIO_BUS
Date: Fri, 22 Feb 2019 20:39:02 +1100 [thread overview]
Message-ID: <20190222093902.GB6006@blackberry> (raw)
In-Reply-To: <20190207045650.18322-1-sjitindarsingh@gmail.com>
On Thu, Feb 07, 2019 at 03:56:50PM +1100, Suraj Jitindar Singh wrote:
> Devices on the KVM_FAST_MMIO_BUS by definition have length zero and are
> thus used for notification purposes rather than data transfer. For
> example eventfd for virtio devices.
>
> This means that when emulating mmio instructions which target devices on
> this bus we can immediately handle them and return without needing to load
> the instruction from guest memory.
>
> For now we restrict this to stores as this is the only use case at
> present.
>
> For a normal guest the effect is negligible, however for a nested guest
> we save on the order of 5us per access.
>
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Thanks, applied to my kvm-ppc-next tree.
Paul.
prev parent reply other threads:[~2019-02-22 9:46 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-07 4:56 [PATCH] KVM: PPC: Book3S HV: Optimise mmio emulation for devices on FAST_MMIO_BUS Suraj Jitindar Singh
2019-02-22 9:39 ` Paul Mackerras [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190222093902.GB6006@blackberry \
--to=paulus@ozlabs.org \
--cc=kvm-ppc@vger.kernel.org \
--cc=kvm@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=sjitindarsingh@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).