From: Thomas Fjellstrom <thomas@fjellstrom.ca>
To: kvm@vger.kernel.org
Subject: virtio disk host cpu overhead?
Date: Fri, 03 Mar 2017 10:05:06 -0700 [thread overview]
Message-ID: <4596416.eghLixMk0z@natasha> (raw)
I've been testing a new samsung 960 evo nvme drive i just got, and running
tests on it in a guest shows a minimum of double the cpu time on the host as
it does on the guest. Somehow a guest running a single thread iozone or fio
test can use 4+ cores on the host side at 50-100%.
I have debian's 4.9.13 kernel installed on the host (4.9.2 on the guest), and
kvm/qemu 2.8.0. I'm using libvirt and virt-manager to set up the guest, with a
lvm volume set up on the nvme drive, and exporting a couple volumes to the
guest which it then either uses lvm on, or testing is done raw on a secondary
volume. (I've tried both)
Host is a consumer box with an AMD 970 board + FX-8320, and 32GB ram. Guest is
currently allocated 8 threads, and 1GB ram which it is currently only using
111MB of while fio is running.
I'm curious to know if this is expected behavior, misconfiguration on my end,
or a misunderstanding of how things work?
I'd appreciate any insight or help anyone is able and willing to provide.
--
Thomas Fjellstrom
thomas@fjellstrom.ca
next reply other threads:[~2017-03-03 19:00 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-03 17:05 Thomas Fjellstrom [this message]
2017-03-10 1:52 ` virtio disk host cpu overhead? Stefan Hajnoczi
2017-03-11 16:33 ` Thomas Fjellstrom
2017-03-11 16:45 ` Paolo Bonzini
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=4596416.eghLixMk0z@natasha \
--to=thomas@fjellstrom.ca \
--cc=kvm@vger.kernel.org \
/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).