Messages in this thread | | | Date | Fri, 04 May 2007 10:57:12 +0400 | From | Alex Tomas <> | Subject | Re: [ext3][kernels >= 2.6.20.7 at least] KDE going comatose when FS is under heavy write load (massive starvation) |
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Andrew Morton wrote: > On Fri, 04 May 2007 10:18:12 +0400 Alex Tomas <alex@clusterfs.com> wrote: > >> Andrew Morton wrote: >>> Yes, there can be issues with needing to allocate journal space within the >>> context of a commit. But >> no-no, this isn't required. we only need to mark pages/blocks within >> transaction, otherwise race is possible when we allocate blocks in transaction, >> then transacton starts to commit, then we mark pages/blocks to be flushed >> before commit. > > I don't understand. Can you please describe the race in more detail?
if I understood your idea right, then in data=ordered mode, commit thread writes all dirty mapped blocks before real commit.
say, we have two threads: t1 is a thread doing flushing and t2 is a commit thread
t1 t2 find dirty inode I find some dirty unallocated blocks journal_start() allocate blocks attach them to I journal_stop()
going to commit find inode I dirty do NOT find these blocks because they're allocated only, but pages/bhs aren't mapped to them start commit
map pages/bhs to just allocate blocks
so, either we mark pages/bhs someway within journal_start()--journal_stop() or commit thread should do lookup for all dirty pages. the latter doesn't sound nice, IMHO.
thanks, Alex
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