From: Paolo Bonzini <pbonzini@redhat.com>
To: Denis Plotnikov <dplotnikov@virtuozzo.com>,
rkrcmar@redhat.com, kvm@vger.kernel.org
Cc: rkagan@virtuozzo.com, den@virtuozzo.com, svt-core@lists.sw.ru
Subject: Re: [PATCH v3 2/6] KVM: x86: switch to masterclock update using timekeeper functionality
Date: Tue, 1 Aug 2017 12:16:06 +0200 [thread overview]
Message-ID: <f233e2f0-e87a-dcbb-9a0c-9447307b1b92@redhat.com> (raw)
In-Reply-To: <82c81e37-9c56-26b9-d8c5-cf87eeb1d470@redhat.com>
A couple more observation now that we've agreed on the approach.
On 01/08/2017 12:03, Paolo Bonzini wrote:
>
>>> Maybe what we want is some kind of "bool cycles_valid", and then
>>> read_clock_and_systime can return it:
>>>
>>>
>>> if (clock->read_clock_and_systime) {
>>> systime_snapshot->cycles_valid =
>>> clock->read_clock_and_systime(
>>> &now, &systime_snapshot->cycles);
Please pass the clocksource to the new function. However this:
> + clock = tk->tkr_mono.clock;
should then be READ_ONCE for the same reason mentioned in
tk_clock_read's comments. Then,
>>> } else {
>>> now = tk_clock_read(&tk->tkr_mono);
this can call clock->read(clock) directly, without going through
tk_clock_read.
Thanks,
Paolo
>>> systime_snapshot->cycles_valid = true;
>>> systime_snapshot->cycles = now;
>>> }
next prev parent reply other threads:[~2017-08-01 10:16 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-29 12:35 [PATCH v3 0/6] make L2's kvm-clock stable, get rid of pvclock_gtod Denis Plotnikov
2017-07-29 12:35 ` [PATCH v3 1/6] pvclock: add parameter to store cycles stamp to pvclock reading function Denis Plotnikov
2017-07-31 14:08 ` Paolo Bonzini
2017-07-29 12:35 ` [PATCH v3 2/6] KVM: x86: switch to masterclock update using timekeeper functionality Denis Plotnikov
2017-07-31 14:20 ` Paolo Bonzini
2017-08-01 9:30 ` Denis Plotnikov
2017-08-01 10:03 ` Paolo Bonzini
2017-08-01 10:16 ` Paolo Bonzini [this message]
2017-08-01 12:11 ` Denis Plotnikov
2017-08-01 12:28 ` Denis Plotnikov
2017-08-01 12:41 ` Paolo Bonzini
2017-08-01 12:46 ` Denis Plotnikov
2017-08-01 17:47 ` Radim Krčmář
2017-07-29 12:35 ` [PATCH v3 3/6] timekeeper: add clocksource change notifier Denis Plotnikov
2017-07-29 12:35 ` [PATCH v3 4/6] KVM: x86: remove not used pvclock_gtod_copy Denis Plotnikov
2017-07-29 12:35 ` [PATCH v3 5/6] pvclock: add clocksource change notification on changing of tsc stable bit Denis Plotnikov
2017-07-31 14:21 ` Paolo Bonzini
2017-07-29 12:35 ` [PATCH v3 6/6] kvmclock: add the clocksource stability querying function Denis Plotnikov
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