From: "Radim Krčmář" <rkrcmar@redhat.com>
To: Avi Cohen <avi.cohen@huawei.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: KVM-Clock
Date: Wed, 24 Feb 2016 13:20:17 +0100 [thread overview]
Message-ID: <20160224122016.GA17209@potion.redhat.com> (raw)
In-Reply-To: <B84047ECBD981D4B93EAE5A6245AA361996018@lhreml501-mbb>
2016-02-24 10:32+0000, Avi Cohen:
>> Look at last paragraph of my previous email.
>> (That one has 1 ns accuracy if KVM is using the masterclock.)
>
> How to make KVM using the masterclock ? - I don't see any masterclock in traces
KVM should use masterclock whenever it can. Host dmesg can contain
warning about unstable TSC if masterclock is not being used for good
reasons (grep for "TSC unstable" and "unstable TSC").
Relevant tracepoints are (from arch/x86/kvm/trace.h)
kvm:kvm_update_master_clock
kvm:kvm_track_tsc
kvm:kvm_pvclock_update
kvm:write_tsc_offset
The host is using TSC clocksource, TSC wasn't marked as unstable, guest
didn't screw with MSR_IA32_TSC or MSR_IA32_TSC_ADJUST, and masterclock
still isn't used?
next prev parent reply other threads:[~2016-02-24 12:20 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <B84047ECBD981D4B93EAE5A6245AA361995B00@lhreml501-mbb>
2016-02-21 16:57 ` KVM-Clock Avi Cohen
2016-02-22 20:08 ` KVM-Clock Radim Krčmář
2016-02-23 7:11 ` KVM-Clock Avi Cohen
2016-02-23 8:04 ` KVM-Clock Wanpeng Li
2016-02-23 8:18 ` KVM-Clock Avi Cohen
2016-02-23 8:38 ` KVM-Clock Avi Cohen
2016-02-23 17:51 ` KVM-Clock Radim Krčmář
2016-02-24 10:32 ` KVM-Clock Avi Cohen
2016-02-24 12:20 ` Radim Krčmář [this message]
2016-02-24 15:31 ` KVM-Clock Avi Cohen
2016-02-24 4:09 ` KVM-Clock Marcelo Tosatti
2016-02-24 8:15 ` KVM-Clock Avi Cohen
2016-02-24 11:33 ` KVM-Clock Marcelo Tosatti
2016-02-24 11:51 ` KVM-Clock Avi Cohen
2016-02-24 12:23 ` KVM-Clock Marcelo Tosatti
2016-02-24 15:27 ` KVM-Clock Avi Cohen
2016-02-24 18:08 ` KVM-Clock Marcelo Tosatti
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=20160224122016.GA17209@potion.redhat.com \
--to=rkrcmar@redhat.com \
--cc=avi.cohen@huawei.com \
--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).