From: Stefan Hajnoczi <stefanha@gmail.com>
To: Clay Andreasen <cda@cray.com>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] High speed polling
Date: Wed, 15 Jun 2011 07:22:22 +0100 [thread overview]
Message-ID: <BANLkTi=yVPCKn8B0hY_ffiW8dBxaJAQFAg@mail.gmail.com> (raw)
In-Reply-To: <4DF7E18F.6050708@cray.com>
On Tue, Jun 14, 2011 at 11:32 PM, Clay Andreasen <cda@cray.com> wrote:
> I have a network device simulation that I am connecting to multiple
> instances of Qemu (nodes) via a shared memory queue. It works pretty well
> as
> long as all of the nodes are initiating communication but when one node is
> passive, it must poll to get packets. So far the fastest I have been able
> to
> get it to poll is about every 2M emulated clocks.
> This is with CONFIG_HIGH_RES_TIMERS and CONFIG_NO_HZ on the host.
> I also set MIN_TIMER_REARM_NS in qemu-timer.c to 100000.
> Is there some way to increase the polling rate by about an order of
> magnitude?
Without more details it's hard to say what is going on:
Running an x86 guest? Are you using ./configure --enable-io-thread?
It sounds like you may not be using KVM? How many vcpus are running
on the host in total compared to the number of logical CPUs on the
host?
You haven't given details on how you are polling in the guest. Are
you running a polling loop in ring 0 or is the guest running a
full-blown OS and polling from userspace?
Why are you polling in the first place - to minimize latency?
Stefan
next prev parent reply other threads:[~2011-06-15 6:22 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-14 22:32 [Qemu-devel] High speed polling Clay Andreasen
2011-06-14 23:12 ` Mulyadi Santosa
2011-06-15 6:22 ` Stefan Hajnoczi [this message]
2011-06-20 16:54 ` Clay Andreasen
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='BANLkTi=yVPCKn8B0hY_ffiW8dBxaJAQFAg@mail.gmail.com' \
--to=stefanha@gmail.com \
--cc=cda@cray.com \
--cc=qemu-devel@nongnu.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).