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=3D230903 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 observ= ed 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 ti= me otherwise spent probing for nonexistent controllers. The Alix series have n= one 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 --=20 You are receiving this mail because: You are the assignee for the bug.=
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