From: Marcelo Tosatti <mtosatti@redhat.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Radim Krcmar <rkrcmar@redhat.com>, kvm list <kvm@vger.kernel.org>
Subject: Re: What's kvmclock's custom sched_clock for?
Date: Thu, 7 Jan 2016 08:56:47 -0200 [thread overview]
Message-ID: <20160107105647.GA6741@amt.cnet> (raw)
In-Reply-To: <CALCETrXv=EfNzeuk5pMtnYKpEpziQ_UtcDtj5=W3+K4qZkSfqw@mail.gmail.com>
On Wed, Jan 06, 2016 at 11:18:51PM -0800, Andy Lutomirski wrote:
> AFAICT KVM reliably passes a monotonic TSC through to guests,
It does not.
> even if the host suspends. That's all that sched_clock needs, I think.
>
> So why does kvmclock have a custom sched_clock?
Migration between hosts with different TSC frequencies.
> On a related note, KVM doesn't pass the "invariant TSC" feature
> through to guests on my machine even though "invtsc" is set in QEMU
> and the kernel host code appears to support it. What gives?
>
> --Andy
prev parent reply other threads:[~2016-01-07 11:03 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-07 7:18 What's kvmclock's custom sched_clock for? Andy Lutomirski
2016-01-07 8:41 ` Andy Lutomirski
2016-01-07 10:59 ` Marcelo Tosatti
2016-01-07 15:18 ` Radim Krcmar
2016-01-07 17:27 ` Andy Lutomirski
2016-01-07 17:48 ` Radim Krcmar
2016-01-07 20:15 ` Marcelo Tosatti
2016-01-07 20:10 ` Marcelo Tosatti
2016-01-08 14:13 ` Radim Krcmar
2016-01-11 21:00 ` Marcelo Tosatti
2016-01-12 15:33 ` Radim Krcmar
2016-01-12 20:48 ` Marcelo Tosatti
2016-01-13 14:59 ` Radim Krcmar
2016-01-07 10:56 ` Marcelo Tosatti [this message]
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