xfs: flush multiple device caches in parallel in xlog_write_iclog

When xlog_write_iclog needs to flush the cache for more than one devices,
the current implementations does this sequentially, which adds up the
flush latency for all devices.  Switch to kicking off all cache flushes
in parallel so that only the longest latency bounds the time of the log
I/O.  This removes the REQ_PREFLUSH optimization for the log device,
but as that flag is never passed on to the device and just very slightly
reduce the latency by queueing the following write from a lower-level
context it is trivially shadowed by the latency improvements of the
parallel flush commands.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

0 files changed, 0 insertions, 0 deletions