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From: Jens Axboe <axboe@kernel.dk>
To: Soheil Hassas Yeganeh <soheil@google.com>,
	linux-kernel@vger.kernel.org, netdev@vger.kernel.org
Cc: Willem de Bruijn <willemb@google.com>,
	Shakeel Butt <shakeelb@google.com>
Subject: Re: [PATCH 6/6] eventpoll: add support for min-wait
Date: Thu, 1 Dec 2022 11:00:52 -0700	[thread overview]
Message-ID: <8d195905-a93f-d342-abb0-dd0e0f5a5764@kernel.dk> (raw)
In-Reply-To: <4764dcbf-c735-bbe2-b60e-b64c789ffbe6@kernel.dk>

>>> @@ -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


  parent reply	other threads:[~2022-12-01 18:01 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-30 22:01 [PATCHSET v3 0/5] Add support for epoll min_wait Jens Axboe
2022-10-30 22:01 ` [PATCH 1/6] eventpoll: cleanup branches around sleeping for events Jens Axboe
2022-10-30 22:01 ` [PATCH 2/6] eventpoll: don't pass in 'timed_out' to ep_busy_loop() Jens Axboe
2022-10-30 22:02 ` [PATCH 3/6] eventpoll: split out wait handling Jens Axboe
2022-10-30 22:02 ` [PATCH 4/6] eventpoll: move expires to epoll_wq Jens Axboe
2022-10-30 22:02 ` [PATCH 5/6] eventpoll: move file checking earlier for epoll_ctl() Jens Axboe
2022-10-30 22:02 ` [PATCH 6/6] eventpoll: add support for min-wait Jens Axboe
2022-11-08 22:14   ` Soheil Hassas Yeganeh
2022-11-08 22:20     ` Jens Axboe
2022-11-08 22:25       ` Willem de Bruijn
2022-11-08 22:29         ` Jens Axboe
2022-11-08 22:44           ` Willem de Bruijn
2022-11-08 22:41       ` Soheil Hassas Yeganeh
2022-12-01 18:00       ` Jens Axboe [this message]
2022-12-01 18:39         ` Soheil Hassas Yeganeh
2022-12-01 18:41           ` Jens Axboe
2022-11-02 17:46 ` [PATCHSET v3 0/5] Add support for epoll min_wait Willem de Bruijn
2022-11-02 17:54   ` Jens Axboe
2022-11-02 23:09     ` Willem de Bruijn
2022-11-02 23:37       ` Jens Axboe
2022-11-02 23:51         ` Willem de Bruijn
2022-11-02 23:57           ` Jens Axboe
2022-11-05 17:39             ` Jens Axboe
2022-11-05 18:05               ` Willem de Bruijn
2022-11-05 18:46                 ` Jens Axboe
2022-11-07 13:25                   ` Willem de Bruijn
2022-11-07 14:19                     ` Jens Axboe
2022-11-07 10:10               ` David Laight
2022-11-07 20:56 ` Stefan Hajnoczi
2022-11-07 21:38   ` Jens Axboe
2022-11-08 14:00     ` Stefan Hajnoczi
2022-11-08 14:09       ` Jens Axboe
2022-11-08 16:10         ` Stefan Hajnoczi
2022-11-08 16:15           ` Jens Axboe
2022-11-08 17:24             ` Stefan Hajnoczi
2022-11-08 17:28               ` Jens Axboe
2022-11-08 20:29                 ` Stefan Hajnoczi
2022-11-09 10:09               ` David Laight
2022-11-10 10:13         ` Willem de Bruijn

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