Re: [PATCH 1/2] udevd: respect the value of TIMEOUT in uevents

[Kay Sievers <kay.sievers@vrfy.org>]

On Tue, May 26, 2009 at 12:19, Alan Jenkins <alan-jenkins@tuffmail.co.uk> wrote:

> Don't apply patch 2 then :-).

No worry, we can not be that fast here. :) We need to get numbers first.

Threads don't come for free, they make udev much less reliable and
harder to debug, compared to the current model. When all events share
the same address space, and the memory for the events gets reused for
forever, a simple bug will likely bring down the entire service,
unlike today where an event process may crash, but the event
management daemon will survive. Actually, I don't remember that the
main udev ever crashed, and that will definitely change with the
threads. :)

I'm not against a threaded udevd, but we should have a good reason to
do it that way. We also need to get numbers on bigger boxes. Udev runs
on boxes with many thousands of events at bootup. we've seen boxes
with 20.000+ disks, where every disk has ~10 devices in sysfs. Some of
the SUSE customers requested to be able to run 4000+ events in
parallel, to bring the bootup time on such boxes down to a reasonable
time. That all works fine with today's udev and we need to be really
careful here.

Thanks,
Kay