From: Paolo Bonzini <pbonzini@redhat.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: kvm list <kvm@vger.kernel.org>,
linux-kernel@vger.kernel.org, X86 ML <x86@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Borislav Petkov <bpetkov@suse.de>
Subject: Re: RFC: Getting rid of LTR in VMX
Date: Mon, 20 Feb 2017 17:02:53 -0500 (EST) [thread overview]
Message-ID: <890292613.23897064.1487628173163.JavaMail.zimbra@redhat.com> (raw)
In-Reply-To: <CALCETrW6sVVQN1DfMvKMpU9u=bpOeS7WZVfwNPYqPqEiysXjFg@mail.gmail.com>
> > Yes. But 150-200 clock cycles are nothing compared to the cache misses
> > you get from preemption, so I'd ignore that. Saving 300 clock cycles on
> > userspace exits from TR+GSBASE would be about 5% on my Haswell.
>
> That's still 5% :)
Yes, 5% on userspace exits is good (though they're rare).
OTOH, 300 clock cycles on preemption are nothing to write home about.
Paolo
next prev parent reply other threads:[~2017-02-20 22:02 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-18 3:29 RFC: Getting rid of LTR in VMX Andy Lutomirski
2017-02-18 15:19 ` Paolo Bonzini
2017-02-20 11:05 ` Paolo Bonzini
2017-02-20 16:46 ` Andy Lutomirski
2017-02-20 16:51 ` Paolo Bonzini
2017-02-20 16:55 ` Andy Lutomirski
2017-02-20 22:02 ` Paolo Bonzini [this message]
2017-02-20 22:23 ` hpa
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=890292613.23897064.1487628173163.JavaMail.zimbra@redhat.com \
--to=pbonzini@redhat.com \
--cc=bpetkov@suse.de \
--cc=hpa@zytor.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@amacapital.net \
--cc=x86@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