Am 29.01.2013 20:09, schrieb Kent Overstreet:
I lied, that idea turned out to be wrong.
Though - data=journal isn't that commonly used, an ext4 bug is an
outside possibility (if it was assuming the pre 2.6.38 semantics of
barriers that could cause this). Could you test with data=ordered and
tell me what happens?
Sorry I didn't state that clearly. The ext4 data=journal test was for
comparison only. All bcache tests were done with defaults, which is
data=ordered.
# mkfs.ext4 -K -b 4096
# mount -o noatime
Disabling all hardware caches with hdparm AND putting bcache in
writethrough mode made it pass the test, btw., with severe performance
loss of course. What's really alarming is that bcache in writeback with
hw caches deactivated still loses transactions. This points to the
journal logic. Maybe the last element of the journal is simply not iterated?
Greetings,
Pierre Beck
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