Re: [RFC 1/4] kevent: core files.

Evgeniy Polyakov
2006-07-31T10:51:17Z

On Mon, Jul 31, 2006 at 08:35:55PM +1000, Herbert Xu (herbert@gondor.apana.org.au) wrote:
> Evgeniy Polyakov <johnpol@2ka.mipt.ru> wrote:
> >
> >> - if there is space, report it in the ring buffer. Yes, the buffer
> >> can be optional, then all events are reported by the system call.
> >
> > That requires a copy, which can neglect syscall overhead.
> > Do we really want it to be done?
>
> Please note that we're talking about events here, not actual data. So
> only the event is being copied, which is presumably rather small compared
> to the data.

In syscall time kevents copy 40bytes for each event + 12 bytes of header
(number of events, timeout and command number). That's likely two cache
lines if only one event is reported.

--
Evgeniy Polyakov