From: Paolo Bonzini <pbonzini@redhat.com>
To: Alex Bligh <alex@alex.org.uk>
Cc: Luigi Rizzo <rizzo@iet.unipi.it>, qemu-devel <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] commit b1bbfe72 causes huge slowdown with no kvm
Date: Wed, 20 Nov 2013 14:55:08 +0100 [thread overview]
Message-ID: <528CBF3C.7060004@redhat.com> (raw)
In-Reply-To: <D98FD4F5-B7C2-4596-A604-0CFB652F764D@alex.org.uk>
Il 20/11/2013 14:47, Alex Bligh ha scritto:
> I think you are saying this sounds like another underlying bug
> (no pause instruction) uncovered by the timer patches rather than
> a bug in the timer patches.
>
> Reading
> http://software.intel.com/file/27087
> perhaps the answer is for pause to yield the lock.
>
> However, what if an arbitrary guest foolishly /does/ do a tight
> spinlock without calling pause?
It would be a problem. I don't think it has to be fixed though (and
anyway of course not now).
The fix could be to make TCG use "real" SMP instead of round-robin.
Paolo
prev parent reply other threads:[~2013-11-20 13:55 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-19 23:00 [Qemu-devel] commit b1bbfe72 causes huge slowdown with no kvm Luigi Rizzo
2013-11-20 9:41 ` Paolo Bonzini
2013-11-20 11:00 ` Luigi Rizzo
2013-11-20 11:19 ` Paolo Bonzini
2013-11-20 13:47 ` Alex Bligh
2013-11-20 13:55 ` Paolo Bonzini [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=528CBF3C.7060004@redhat.com \
--to=pbonzini@redhat.com \
--cc=alex@alex.org.uk \
--cc=qemu-devel@nongnu.org \
--cc=rizzo@iet.unipi.it \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.