Messages in this thread | | | Date | Wed, 11 Oct 2023 16:30:26 +0800 | Subject | Re: Re: [PATCH 01/15] sched/fair: Add avg_vruntime | From | Abel Wu <> |
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On 10/11/23 3:30 PM, Peter Zijlstra Wrote: > On Wed, Oct 11, 2023 at 12:15:28PM +0800, Abel Wu wrote: >> On 5/31/23 7:58 PM, Peter Zijlstra wrote: >>> +/* >>> + * Compute virtual time from the per-task service numbers: >>> + * >>> + * Fair schedulers conserve lag: >>> + * >>> + * \Sum lag_i = 0 >>> + * >>> + * Where lag_i is given by: >>> + * >>> + * lag_i = S - s_i = w_i * (V - v_i) >> >> Since the ideal service time S is task-specific, should this be: >> >> lag_i = S_i - s_i = w_i * (V - v_i) > > It is not, S is the same for all tasks. Remember, the base form is a > differential equation and all tasks progress at the same time at dt/w_i > while S progresses at dt/W.
IIUC it's V progresses at dt/W and is same for all tasks, not S which is measured in real time (V*w_i).
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