On Sun, Nov 27, 2011 at 2:44 AM, Kay Sievers <[email protected]> wrote: > On Sat, Nov 26, 2011 at 22:52, Stefan Majewsky > <[email protected]> wrote: >> my openSUSE 12.1 system boots in about 30 seconds, and I wanted to cut >> that time down a bit, so I took a look at systemd-analyze's blame and >> plot output. >> >> But I do not really know how to interpret the results which I see in >> the plot [1]. The startup sequence takes 20.5 seconds in userspace, of >> which only the last 3 seconds seem to be spent on what I consider "the >> interesting stuff": starting all sorts of services and finally >> bringing up KDM. >> >> The rest of the time seems to be spent activating the hardware, >> various mounts and udev. (According to the LED on my notebook's case, >> the disk is busy all the time.) To put my confusion into questions: >> >> 1. Why does the system need 6 seconds (from t=6.3s to t=12.3s on the >> plot) to activate some tmpfs mounts? >> >> 2. Why is localnet.service activating for a whole 7 seconds? I looked >> into it, it's only a SysV init script that sets hostname and >> domainname from the config in /etc, yet it's number 1 in >> systemd-analyze blame. >> >> 3. Why does it look like about nothing happens between t=13s and t=22s? >> >> It might be that openSUSE's unit files (or SysV leftovers) are not yet >> optimized for the early boot: For example, I seem to have saved some >> seconds by masking lvm.service (I don't use LVM at all). But that >> won't explain why systemd is actually slower on this stage of boot vs. >> the old SysV init some distro versions ago. >> >> Can someone enlighten me? > > These numbers just look like a slower disk. The timing graph is not > really useful if things wait for I/O. The old SUSE boot was in some > cases better optimized for slower rotating media than systemd is. How > fast is the disk? Try hdparm -t /dev/sda > > The filesystem is ext4? This is an updated or newly installed system? > The filesystem is formatted a while back? We've seen strange ext4 > performance numbers on older filesystems, that just went away after > reformatting. We have no real idea what's causing this, maybe some > weird fragmentation issue.
Kay, do you really think slow media is the only reason? I could check the plot right now and there is a super-strange delay from t=4.5 to t=6.5 (before doing anything at all). Later on there is the delay for mounts, those I agree may be related to slow media. But again from 13 to 22 it's basically waiting udev events... which is too much! I'd check a fresh install to avoid problem with legacy udev rules... I recall when I moved my gentoo from openrc to systemd I had a "hotplug" package (http://linux-hotplug.sourceforge.net) doing nothing useful. Then I went to notice my kernel was also configured to call /sbin/hotplug even tho it did not exist was raising pid count, etc. Last but not least, Kay you could write an article similar to Lennart's blogs about the proper systemd+udev setup, like "systemd + udev for packagers". People are doing crazy things! :-( -- Gustavo Sverzut Barbieri http://profusion.mobi embedded systems -------------------------------------- MSN: [email protected] Skype: gsbarbieri Mobile: +55 (19) 9225-2202 _______________________________________________ systemd-devel mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/systemd-devel
