Re: [PATCH] /dev/epoll update ...

Dan Kegel (
Tue, 25 Sep 2001 02:25:31 -0700

Jamie Lokier wrote:
> > Anyway there's a pretty good patch ( ),
> > that has been tested here :
> >
> >
> >
> > that implement the signal-per-fd mechanism and it achieves a very good
> > scalability too.
> It has the bonus of requiring no userspace changes too. Lovely!

Well, not quite *no* userspace changes, but not many. You have to
use si_band rather than si_code (and with Luban's version, you also
need to set a new flag).

It has some locking problems that only show up under very heavy use,
so caveat emptor. I put together a stress test
( with the -sf option);
run that against betaftpd, and around 4500 ftp sessions, you might
see it crash because a signal comes in while the file table is expanding...

(By the way, I finally updated to
distinguish properly between edge-triggered readiness notification
methods and level-triggered ones. Hope that helps dispel some
confusion in the future.)
- Dan
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