Op 9 mei 2011, om 22:23 heeft Kay Sievers het volgende geschreven: > On Mon, May 9, 2011 at 22:08, Lennart Poettering <lenn...@poettering.net> > wrote: >> On Mon, 09.05.11 22:02, Lennart Poettering (lenn...@poettering.net) wrote: >> >>>> It's still in the 10 second range on a 600MHz cortex-a8 machine >>>> booting from an SD card. I need to dig out my 400MHz arm920t to see >>>> how long it takes there. So having udev-less operation in systemd >>>> would be nice, even if it's only used on 'embedded' >>> >>> Have you checked what precisely takes so long? My guess is that some >>> driver has a slow sysfs uevent trigger callback, and that might be >>> fixable in the driver. You might want to use strace with timestamps to >>> figure out why udev trigger might be so slow. >> >> Also note that only very few devices are exposed and depended on by >> systemd. In an embedded env you might be able to simple trigger those >> explicitly first, and then trigger the rest afterwards. That way you >> don't have to wait 10s, and the triggering will be dispatched in the bg, >> but you still get the flexibility that udev can handle hotplugged >> devices. >> >> Kay, opinions? > > Guess that should work fine. I guess we could short-cut some stuff too > if it helps for custom setups, so systemd would look if the device is > already there, instead of wait for the tag to show up. But we would > need to find out if that really helps.
Here's a systemd-analyze plot with udev 168: http://dominion.thruhere.net/koen/angstrom/systemd/168.svg That's run on a beagleboard C3 running at 500Mhz on a 2GB sandisk SD card (±10MB/s read/write) > Real numbers of the most recent udev on such systems would help, so we > get an idea what we are dealing with. > > Things like: > time (udevadm trigger; udevadm settle) > would be good to know too. If that looks like something to fix, the output of: > udevadm monitor > during the trigger command above will be useful too. I'll do that later today. regards, Koen _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
