Re: [RFC PATCH 0/3] epoll: read(),write(),ioctl() interface

From: Nathaniel Yazdani
Date: Mon Feb 03 2014 - 14:42:13 EST

On 2/3/14, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
> On 02/02/2014 06:17 PM, Nathaniel Yazdani wrote:
>> Hi everyone,
>> This patch series adds support for read(), write(), and ioctl()
>> operations
>> on eventpolls as well as an associated userspace structure to format the
>> eventpoll entries delivered via read()/write() buffers. The new
>> structure,
>> struct epoll, differs from struct epoll_event mainly in that it also
>> holds
>> the associated file descriptor. Using the normal I/O interface to
>> manipulate
>> eventpolls is much neater than using epoll-specific syscalls while also
>> allowing for greater flexibility (theoretically, pipes could be used to
>> filter access). Specifically, write() creates, modifies, and/or removes
>> event
>> entries stored in the supplied buffer, using the userspace identifier to
>> check whether an entry exists and removing it if no events are set to
>> trigger
>> it, while read() simply waits for enough events to fill the provided
>> buffer.
>> As timeout control is essential for polling to be practical, ioctl() is
>> used
>> to configure an optional timeout, which is infinite by default.
> If major changes are made to the epoll API, I want a way to do a bunch
> of EPOLL_CTL_MODs and a wait, all in one syscall. Even better: allow
> more flexible timeouts (CLOCK_MONOTONIC, CLOCK_REALTIME, etc) at the
> same time.
> Since this can't do that, I'm not terribly inspired.
> --Andy

So are you saying that those features you mentioned are specifically sought
after for the kernel? If so I'd like to take a crack at some of them,
may as well
get some use out of my new knowledge of epoll internals :)

Thanks for your input,
Nate Yazdani
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