Messages in this thread | | | Date | Wed, 12 Mar 2003 13:05:39 +0100 | From | bert hubert <> | Subject | Re: [patch, rfc] lt-epoll ( level triggered epoll ) ... |
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On Tue, Mar 11, 2003 at 10:20:38AM -0800, Davide Libenzi wrote:
> > Most programs will not abandon 'legacy' interfaces like poll and select and > > will only want to offer epoll in addition. Right now that is hard to do. > > I agree here. It took 15 minutes to port thttpd to LT epoll.
Having level ability will massively speed up epoll adoption. By the way, was there a reason to go to edge in the first place?
> I received a bunch of private emails ( ppl that are using ET epoll ) > asking me to have both behaviours. The code require no more than 10 lines > of code to give both possibilities. We have two options in doing that :
Impressive.
> We add a parameter to epoll_create() that will set the interface behaviour > at creation time : ... > We can go at fd granularity by leaving the API the same, and we define : > #define EPOLLET (1 << 31)
This last option would retain the current ABI *and* semantics for unchanged programs. I do wonder if there is a case where you'd want to run in mixed mode, however. But if the code to support mixed operation is truly trivial, I think we should not set policy from the kernel ('only do epoll in one mode') and leave it up to userspace to discover if there is a use for this.
Anyhow, as a member of the kCowSay [1] association of userspace people meddling in the affairs of kernel coders, I vote strongly for having level triggered epoll on the kernel, with the ability to do mixed mode.
Regards,
bert
[1] Founded by John Levon on the assumption that kernel coders assume all userspace code to be trivial, so we should have a massively trivial name. kCowSay tries to educate kernel deities about the needs of us userspace dwellers.
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