Messages in this thread | | | Date | Mon, 20 Nov 2006 11:51:59 +0300 | From | Evgeniy Polyakov <> | Subject | Re: [take24 0/6] kevent: Generic event handling mechanism. |
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On Mon, Nov 20, 2006 at 12:43:01AM -0800, Andrew Morton (akpm@osdl.org) wrote: > > > >If thread calls kevent_wait() it means it has processed previous entries, > > > >one can call kevent_wait() with $num parameter as zero, which > > > >means that thread does not want any new events, so nothing will be > > > >copied. > > > > > > This doesn't solve the problem. You could only request new events when > > > all previously reported events are processed. Plus: how do you report > > > events if the you don't allow get_event pass them on? > > > > Userspace should itself maintain order and possibility to get event in > > this implementation, kernel just returns events which were requested. > > That would mean that in a multithreaded application (or multi-processes > sharing the same MAP_SHARED ringbuffer), all threads/processes will be > slowed down to wait for the slowest one.
Not at all - all other threads can call kevent_get_events() with theirs own place in the ring buffer, so while one of them is processing an entry, others can fill next entries.
> > > >They all already imeplemented. Just all above, and it was done several > > > >months ago already. No need to reinvent what is already there. > > > >Even if we will decide to remove kevent_get_events() in favour of ring > > > >buffer-only implementation, winting-for-event syscall will be > > > >essentially kevent_get_events() without pointer to the place where to > > > >put events. > > > > > > Right, but this limitation of the interface is important. It means the > > > interface of the kernel is smaller: fewer possibilities for problems and > > > fewer constraints if in future something should be changed (and smaller > > > kernel). > > > > Ok, lets see for ring buffer implementation right now, and then we will > > decide if we want to remove or to stay with kevent_get_events() syscall. > > I agree that kevent_get_events() is duplicative and we shouldn't need it. > Better to concentrate all our development effort on the single and most > flexible means of delivery.
Let's wait for ring buffer imeplementation first :)
-- Evgeniy Polyakov - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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