From: Radim Krcmar <rkrcmar@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>, kvm list <kvm@vger.kernel.org>
Subject: Re: What's kvmclock's custom sched_clock for?
Date: Fri, 8 Jan 2016 15:13:16 +0100 [thread overview]
Message-ID: <20160108141316.GC12375@potion.brq.redhat.com> (raw)
In-Reply-To: <20160107201043.GA18469@amt.cnet>
2016-01-07 18:10-0200, Marcelo Tosatti:
> On Thu, Jan 07, 2016 at 04:18:11PM +0100, Radim Krcmar wrote:
>> Stable sched clock is quite unrelated to TSC features. KVMs from last
>> few years should always give good enough result to allow stable sched
>> clock. We wanted realtime guests and realtime linux needs no_hz=full
>> that depends on stable sched clock. The result is huge hack.
>>
>> We'd need to say that migration creates powerful gravity fields to
>> faithfully migrate constant/invariant TSC, but stable sched clock
>> doesn't have that strict expectations about time.
>
> Was that supposed to be a joke?
Yes, if you mean the first sentence of the second paragraph.
(I think that we'll use a different disclaimer when we enable
best-effort migration with invariant TSC.)
next prev parent reply other threads:[~2016-01-08 14:13 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 [this message]
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
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