linux-kernel - RE: [PATCHSET v3 0/5] Add support for epoll min

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Message-ID: <d7fe932b7ad044e2bfc93c6b12131c2a@AcuMS.aculab.com>
Date:   Wed, 9 Nov 2022 10:09:33 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Stefan Hajnoczi' <stefanha@...hat.com>,
        Jens Axboe <axboe@...nel.dk>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [PATCHSET v3 0/5] Add support for epoll min_wait

From: Stefan Hajnoczi
> Sent: 08 November 2022 17:24
...
> The way the current patches add min_wait into epoll_ctl() seems hacky to
> me. struct epoll_event was meant for file descriptor event entries. It
> won't necessarily be large enough for future extensions (luckily
> min_wait only needs a uint64_t value). It's turning epoll_ctl() into an
> ioctl()/setsockopt()-style interface, which is bad for anything that
> needs to understand syscalls, like seccomp. A properly typed
> epoll_wait3() seems cleaner to me.

Is there any reason you can't use an ioctl() on an epoll fd?
That would be cleaner that hacking at epoll_ctl().

It would also be easier to modify to allow (strange) things like:
- return if no events for 10ms.
- return 200us after the first event.
- return after 10 events.
- return at most 100 events.

	David

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