netdev - Re: [PATCH 6/6] eventpoll: add support for min-wait

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Message-ID: <8d195905-a93f-d342-abb0-dd0e0f5a5764@kernel.dk>
Date:   Thu, 1 Dec 2022 11:00:52 -0700
From:   Jens Axboe <axboe@...nel.dk>
To:     Soheil Hassas Yeganeh <soheil@...gle.com>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Cc:     Willem de Bruijn <willemb@...gle.com>,
        Shakeel Butt <shakeelb@...gle.com>
Subject: Re: [PATCH 6/6] eventpoll: add support for min-wait

>>> @@ -1845,6 +1891,18 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
>>>  		ewq.timed_out = true;
>>>  	}
>>>  
>>> +	/*
>>> +	 * If min_wait is set for this epoll instance, note the min_wait
>>> +	 * time. Ensure the lowest bit is set in ewq.min_wait_ts, that's
>>> +	 * the state bit for whether or not min_wait is enabled.
>>> +	 */
>>> +	if (ep->min_wait_ts) {
>>
>> Can we limit this block to "ewq.timed_out && ep->min_wait_ts"?
>> AFAICT, the code we run here is completely wasted if timeout is 0.
> 
> Yep certainly, I can gate it on both of those conditions.
Looking at this for a respin, I think it should be gated on
!ewq.timed_out? timed_out == true is the path that it's wasted on
anyway.

-- 
Jens Axboe