Messages in this thread |  | | | From | Neil Brown <> | | Date | Sat, 17 Jun 2006 08:25:14 +1000 | | Subject | Re: [patch 0/5] [PATCH,RFC] vfs: per-superblock unused dentries list (2nd version) |
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On Friday June 16, jblunck@suse.de wrote: > On Mon, Jun 05, Neil Brown wrote: > > > I understand that this is where problem is because the selected > > dentries don't stay at the end of the list very long in some > > circumstances. In particular, other filesystems' dentries get mixed > > in. > > No. The problem is that the LRU list is too long and therefore unmounting > seems to take ages. >
But I cannot see that the whole LRU list needs to be scanned during unmount. The only thing that does that is shrink_dcache_sb, which is used: in do_remount_sb in __invalidate_device in a few filesystems (autofs, coda, smbfs) and not when unmounting the filesystem (despite the comment).
(This is in 2.6.17-ec6-mm2).
I can see that shrink_dcache_sb could take a long time and should be fixed, which should be as simple as replacing it with shrink_dcache_parent; shrink_dcache_anon.
But I'm still puzzled as to why a long dcache LRU slows down unmounting.
Can you give more details?
Thanks, NeilBrown
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