Re: [PATCH] eventfd: support delayed wakeup for non-semaphore eventfd to reduce cpu utilization

From: Bagas Sanjaya
Date: Mon Apr 17 2023 - 04:23:37 EST


On Sun, Apr 16, 2023 at 07:31:55PM +0800, wenyang.linux@xxxxxxxxxxx wrote:
> +eventfd_wakeup_delay_msec
> +------------------

Please match the section underline length as the section text above.

> +Frequent writing of an eventfd can also lead to frequent wakeup of the peer
> +read process, resulting in significant cpu overhead.
> +How ever for the NON SEMAPHORE eventfd, if it's counter has a nonzero value,
> +then a read(2) returns 8 bytes containing that value, and the counter's value

reading eventfd?

> +is reset to zero.
> +So it coule be optimized as follows: N event_writes vs ONE event_read.
> +By adding a configurable delay after eventfd_write, these unnecessary wakeup
> +operations are avoided.

What is the connection from optimization you described to eventfd_write
delay?

Thanks.

--
An old man doll... just what I always wanted! - Clara

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