Date: Sun, 26 Aug 2018 05:09:25 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 230903] remount root readonly slow on Alix Message-ID: <bug-230903-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=230903 Bug ID: 230903 Summary: remount root readonly slow on Alix Product: Base System Version: 11.2-STABLE Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: sthalik@tehran.lain.pl Hey, On this Alix machine, mounting root readonly after mounting it read-write is slow, as in: % mount -w / % time mount -r / # 15-20 seconds A workaround is to mount the partition async in which case the remount is almost instant. My typical workflow is to mount read-write, break something, then remount read-only for the sake of fsck(8). The original Alix series use a Compact Flash -> ATA controller. I've observed this behavior with multiple CF cards. Typical WCHAN is `biowr', `wdrain' or both. This behavior persists since at least FreeBSD 10 series. Note, the CF storage isn't that slow, see: cat /usr/lib/* > /dev/null 0.10s user 1.21s system 46% cpu 2.821 total cat /usr/bin/* > /dev/null 0.12s user 3.09s system 67% cpu 4.756 total There are some nasty things in KERNCONF, only to reduce logspam and save time otherwise spent probing for nonexistent controllers. The Alix series have none of these controllers: -->-- include GENERIC [trivia] nooptions SMP nooptions APIC_IO nodevice acpi nodevice xenpci # fix build nooptions XENHVM # idem nodevice hyperv # idem --<-- I can attach various config files (sysctl.conf, rc.conf, dmesg.boot, fstab, KERNCONF) if necessary but they look sane other than the aforementioned KERNCONF. cheers, sh -- You are receiving this mail because: You are the assignee for the bug.help
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