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Re: [PATCH v5 11/12] migration/dirtyrate: Implement qmp_cal_dirty_rate()
From: |
David Edmondson |
Subject: |
Re: [PATCH v5 11/12] migration/dirtyrate: Implement qmp_cal_dirty_rate()/qmp_get_dirty_rate() function |
Date: |
Thu, 27 Aug 2020 12:58:48 +0100 |
On Thursday, 2020-08-27 at 17:34:13 +08, Zheng Chuan wrote:
>>> + /*
>>> + * Only support query once for each calculation,
>>> + * reset as DIRTY_RATE_STATUS_UNSTARTED after query
>>> + */
>>> + (void)dirtyrate_set_state(&CalculatingState, CalculatingState,
>>> + DIRTY_RATE_STATUS_UNSTARTED);
>>
>> Is there a reason for this restriction? Removing it would require
>> clarifying the state model, I suppose.
>>
> We only support query once for each calculation.
> Otherwise, it could always query dirtyrate, but maybe the dirtyrate is
> calculated
> long time ago.
There's nothing in the current interface that prevents this from being
the case already - the caller could initiate a 1 second sample, then
wait 24 hours to query the result.
Obviously this would generally be regarded as "d'oh - don't do that",
but the same argument would apply if the caller is allowed to query the
results multiple times.
Perhaps a complete solution would be to include information about the
sample period with the result. The caller could then determine whether
the sample is of adequate quality (sufficiently recent, taken over a
sufficiently long time period) for its' intended use.
dme.
--
I walk like a building, I never get wet.
- [PATCH v5 03/12] migration/dirtyrate: Add RamlockDirtyInfo to store sampled page info, (continued)
[PATCH v5 04/12] migration/dirtyrate: Add dirtyrate statistics series functions, Chuan Zheng, 2020/08/24
[PATCH v5 11/12] migration/dirtyrate: Implement qmp_cal_dirty_rate()/qmp_get_dirty_rate() function, Chuan Zheng, 2020/08/24
- Re: [PATCH v5 11/12] migration/dirtyrate: Implement qmp_cal_dirty_rate()/qmp_get_dirty_rate() function, David Edmondson, 2020/08/26
- Re: [PATCH v5 11/12] migration/dirtyrate: Implement qmp_cal_dirty_rate()/qmp_get_dirty_rate() function, Zheng Chuan, 2020/08/27
- Re: [PATCH v5 11/12] migration/dirtyrate: Implement qmp_cal_dirty_rate()/qmp_get_dirty_rate() function,
David Edmondson <=
- Re: [PATCH v5 11/12] migration/dirtyrate: Implement qmp_cal_dirty_rate()/qmp_get_dirty_rate() function, Zheng Chuan, 2020/08/27
- Re: [PATCH v5 11/12] migration/dirtyrate: Implement qmp_cal_dirty_rate()/qmp_get_dirty_rate() function, David Edmondson, 2020/08/27
- Re: [PATCH v5 11/12] migration/dirtyrate: Implement qmp_cal_dirty_rate()/qmp_get_dirty_rate() function, Zheng Chuan, 2020/08/27
- Re: [PATCH v5 11/12] migration/dirtyrate: Implement qmp_cal_dirty_rate()/qmp_get_dirty_rate() function, David Edmondson, 2020/08/27
[PATCH v5 02/12] migration/dirtyrate: add DirtyRateStatus to denote calculation status, Chuan Zheng, 2020/08/24
[PATCH v5 05/12] migration/dirtyrate: move RAMBLOCK_FOREACH_MIGRATABLE into ram.h, Chuan Zheng, 2020/08/24
[PATCH v5 01/12] migration/dirtyrate: setup up query-dirtyrate framwork, Chuan Zheng, 2020/08/24
[PATCH v5 06/12] migration/dirtyrate: Record hash results for each sampled page, Chuan Zheng, 2020/08/24