Messages in this thread | | | From | Tom Zanussi <> | Date | Tue, 22 Apr 2003 01:00:55 -0500 | Subject | RE: [patch] printk subsystems |
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Perez-Gonzalez, Inaky writes: > > > From: Tom Zanussi [mailto:zanussi@us.ibm.com] > > > > It seems to me that when comparing apples to apples, namely > > considering the complete lifecycle of an event, ... <snip> > > > > While kue_send_event() in itself is very simple and efficient, it's > > only part of the story, the other parts being the copy_to_user() ... > > Agreed - my mistake here in the comparison for leaving out that stuff. > > > event. While kue can avoid this kernel-side copy, it's not possible > > for it to avoid the copy_to_user() since its design precludes mmapping > > the kernel data. Again, six of one, half dozen of another. kue looks > > Sure - those things, I would say, they compensate one another, > except for that mmap() detail that pushes the balance towards relayfs > regarding effectiveness when delivering the messages; I think that > at the end the difference should not be too big as the copying of > the data in kue to user space should roughly compensate by the copying > of the data to the relayfs buffer; after all, a copy is a copy. > No data to back this claim though, I am just thinking a mental > schematic of the lifetime of a bit in both systems out loud. >
Right. This is what I meant when I said the two were very similar when considering the lifetime of a single event, ignoring everything else such as bulk processing via mmap() vs. iterating through a list, as discussed elsewhere.
> Or, again, I am missing something ... > > Iñaky Pérez-González -- Not speaking for Intel -- all opinions are my own > (and my fault) >
-- Regards,
Tom Zanussi <zanussi@us.ibm.com> IBM Linux Technology Center/RAS
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