Re: [PATCH v2 5/7] sched/fair: Increase weight bits for avg_vruntime

[K Prateek Nayak <kprateek.nayak@amd.com>]

On 4/2/2026 4:26 PM, K Prateek Nayak wrote:
>> That is, something like the below... But with a comment ofc :-)
>>
>> Does that make sense?
> 
> Let me go queue an overnight test to see if I trip that warning or
> not.

Didn't trip any warning and the machine is still up and running
after 15 Hours so feel free to include:

Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>

Perhaps the comment can read something like:

		/*
		 * A heavy entity can pull the avg_vruntime close to its
		 * vruntime post enqueue but the zero_vruntime point is
		 * only updated at the next update_deadline() / enqueue
		 * / dequeue.
		 *
		 * Until then, the sum_w_vruntime grow quadratically,
		 * proportional to the entity's weight (w_i) as:
		 *
		 *   sum_w_vruntime -= (lag_i * (W + w_i) / W) * w_i
		 *
		 * If w_i > W, it is beneficial to pull the
		 * zero_vruntime towards the entity's vruntime (V_i)
		 * since the sum_w_vruntime would only grow  by
		 * (lag_i * W) which consumes lesser bits than leaving
		 * the zero_vruntime at the pre-enqueue avg_vruntime.
		 */
		if (weight > load)
			update_zero = true;

Feel free to reword as you see fit :-)

-- 
Thanks and Regards,
Prateek