From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Tianyu Lan <ltykernel@gmail.com>
Cc: Yubo Xie <yuboxie@microsoft.com>,
linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org, Tianyu Lan <Tianyu.Lan@microsoft.com>,
kys@microsoft.com, haiyangz@microsoft.com,
sthemmin@microsoft.com, liuwe@microsoft.com,
daniel.lezcano@linaro.org, tglx@linutronix.de,
michael.h.kelley@microsoft.com
Subject: Re: [PATCH] x86/Hyper-V: Fix hv sched clock function return wrong time unit
Date: Wed, 25 Mar 2020 15:28:45 +0100 [thread overview]
Message-ID: <87lfno5x0i.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <039e126f-f00d-d7e1-aa92-c049c9e3333b@gmail.com>
Tianyu Lan <ltykernel@gmail.com> writes:
>>> @@ -398,7 +399,8 @@ static u64 notrace read_hv_clock_msr_cs(struct clocksource *arg)
>>>
>>> static u64 read_hv_sched_clock_msr(void)
>>> {
>>> - return read_hv_clock_msr() - hv_sched_clock_offset;
>>> + return (read_hv_clock_msr() - hv_sched_clock_offset)
>>> + * (NSEC_PER_SEC / HV_CLOCK_HZ);
>>> }
>>
>> kvmclock seems to have the same (pre-patch) code ...
>
>
> kvm sched clock gets time from pvclock_clocksource_read() and
> the time unit is nanosecond. So there is such issue in KVM code.
>
Ah, true, kvmclock is always 1Ghz so it's reading 'naturally' converts
to ns.
--
Vitaly
next prev parent reply other threads:[~2020-03-25 14:28 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-24 15:19 [PATCH] x86/Hyper-V: Fix hv sched clock function return wrong time unit Yubo Xie
2020-03-24 15:49 ` Vitaly Kuznetsov
2020-03-25 13:57 ` Tianyu Lan
2020-03-25 14:28 ` Vitaly Kuznetsov [this message]
2020-03-25 1:02 ` Sasha Levin
2020-03-25 18:46 ` Dexuan Cui
2020-03-25 18:57 ` Yubo Xie
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