Bug 709014
| Summary: | Optimisation request: selinux costs several seconds during boot (out of 30 total) on old Celeron-M 630 Mhz | ||
|---|---|---|---|
| Product: | [Fedora] Fedora | Reporter: | Alan Jenkins <alan.christopher.jenkins> |
| Component: | systemd | Assignee: | systemd-maint |
| Status: | CLOSED WONTFIX | QA Contact: | Fedora Extras Quality Assurance <extras-qa> |
| Severity: | unspecified | Docs Contact: | |
| Priority: | unspecified | ||
| Version: | 15 | CC: | dwalsh, eparis, ewalsh, harald, herrold, johannbg, john, lpoetter, metherid, mgrepl, mschmidt, notting, plautrba, sdsmall, tmraz |
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | i686 | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: |
EeePC 701 ("EeePC 4G")
|
|
| Last Closed: | 2011-12-16 00:35:12 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
|
Description
Alan Jenkins
2011-05-30 12:00:16 UTC
uh... caveats 1) The systemd-analyze comparison may not be the full story. Bootchart doesn't show such a difference. It *does* show a reduction in cpu usage of specific processes: 4s less in udevd, 1.5s less in systemd-tmpfiles. IMO Bootchart is considering the boot process to end later, in the selinux-disabled case, but it's not as clear as I'd like. Also, bootup still looks more cpu-bound than io-bound. The 1.5s delay in systemd-tempfiles can easily be reproduced outside the boot process. 2) I should have said I'm running KDE. So the startup of the login manager is probably a bit different to a default fedora install. And this may be affecting the way systemd / bootchart measure the boot process. This time is spent compiling regular expressions in order to setup proper labeling. We could make systemd a little smarter about its labeling in that it does not need to load all regular expressions at boot, and we could allow it to load them more on demand. /dev /var/run /tmp Perhaps. To nitpick: when I looked at the 1.5s delay in systemd-tmpfiles, 60% of it was spent in a strcmp() implementation, which callgrind says is called literally 8 million times. I didn't have the debuginfo to see the caller, but it doesn't sound regex-y. I just checked the selinux source, and found nodups_specs() doing O(n^2) string comparisons which fits almost exactly, for n ~= 4000. If those strcmp()s could be eliminated, it should save at least 1.5s * 60% * 2 ~= 1.5s. (label_init() is used at least twice, in both systemd and systemd-tmpfiles). I would guess we should only do this at compile time. Not sure what problems this would solve except print an error message. Seems like something we should be able to optionally check. This package has changed ownership in the Fedora Package Database. Reassigning to the new owner of this component. libselinux in F16 has improved in this regard. It's not doing the O(n^2) dups check anymore. I don't think performance improvements will be backported to F15, so WONTFIX for that release. Please reopen and change the Version field if the problem is reproducible in the latest Fedora release. |