2007/5/30, Phillip Susi [EMAIL PROTECTED]:
Stefan Bader wrote:
Since drive a supports barrier request we don't get -EOPNOTSUPP but
the request with block y might get written before block x since the
disk are independent. I guess the chances of this are quite low since
at some point
The order that these are expected by the filesystem to hit stable
storage are:
1. block 4 and 10 on stable storage in any order
2. barrier block X on stable storage
3. block 5 and 20 on stable storage in any order
The point I'm trying to make is that in XFS, block 5 and 20 cannot
be allowed to
in-flight I/O to go to zero?
Something like that is needed for some dm targets to support barriers.
(We needn't always wait for *all* in-flight I/O.)
When faced with -EOPNOTSUP, do all callers fall back to a sync in
the places a barrier would have been used, or are there any more
sophisticated
2007/5/25, Neil Brown [EMAIL PROTECTED]:
BIO_RW_FAILFAST: means low-level driver shouldn't do much (or no)
error recovery. Mainly used by mutlipath targets to avoid long SCSI
recovery. This should just be propagated when passing requests on.
Is it much or no?
Would it be reasonable to use
to it but this at least causes queues
to be flushed immediately instead of waiting for more requests for a
short time. Should also just be passed on. Otherwise performance gets
poor since something above will rather wait for the current
request/bio to complete instead of sending more.
Stefan Bader
