On Fri, Mar 18, 2011 at 12:35 PM, fykc...@gmail.com <fykc...@gmail.com> wrote: > Hi all, > > We did a series boot-time tests of systemd, and found some interesting things: > (Note the tests were performed on a laptop with a 4-core mips cpu, AMD > RS780 chipset, 2GB Memory, rotate harddisk with ext4 filesystem, > debian squeeze, Linux 2.6.36 with fanotify enabled, systemd-v20, only > boot to console.) > > 1. What can readahead affect boot-time? > Sadly observed negative affect -- boot-time increases at least 1s.
>From subjective feelings (no real measurements) I confirm it. > With bootchart, I find more I/O at boot compared with no readahead, > see attachment noreadahead-vs-readahead.png. > Thoughts: Maybe we need only monitor files with read access, not all > opend files? P.S. inotify seems enough for the job (with one more step > to open each file). > > 2. udev-settle.service serializes the boot process, see attachment > udev-settle.png. I have feeling that increased parallelism during boot (like starting fsck/mount as soon as device becomes available) actually has negative effect on consumer grade devices. My HDD in notebook simply is not prepared for it ... > I tried to create a hotplug.target(which is activated after > default.target), and made udev-settle reside at it, this rendered a > unbootable system. systemd depends on udev at early time. > Thoughts: devtmpfs is mounted, so all cold-plug jobs can be done > without udev involved. > IMHO, fast boot doesn't mean get all services ready in a short time, > but means popup an UI as soon as possible. Windows seems do hotplug > jobs after user log in. > Mandriva uses so called "speedboot" with sysvint - where GUI is started as soon as possible. It is handcrafted so that only several device classes are coldplugged and then DM is launched effectively from rc.sysinit already. Users did mention that boot under systemd actually feels slower then using sysvinit. > BTW, bootchart seems not very intuitive(no service, only processes. > Also some processes may be missed if they live between two "ps aux" > call of bootchart), is it possible to add similar feature to systemd? > > > > -- > Regards, > - cee1 > > _______________________________________________ > systemd-devel mailing list > systemd-devel@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/systemd-devel > > _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
