Boaz Harrosh 7de6e28417 pnfs-obj: Better IO pattern in case of unaligned offset ... Depending on layout and ARCH, ORE has some limits on max IO sizes which is communicated on (what else) ore_layout->max_io_length, which is always stripe aligned. This was considered as the pg_test boundary for splitting and starting a new IO. But in the case of a long IO where the start offset is not aligned what would happen is that both end of IO[N] and start of IO[N+1] would be unaligned, causing each IO boundary parity unit to be calculated and written twice. So what we do in this patch is split the very start of an unaligned IO, up to a stripe boundary, and then next IO's can continue fully aligned til the end. We might be sacrificing the case where the full unaligned IO would fit within a single max_io_length, but the sacrifice is well worth the elimination of double calculation and parity units IO. Actually the sacrificing is marginal and is almost unmeasurable. TODO: If we know the total expected linear segment that will be received, at pg_init, we could use that information in many places: 1. blocks-layout get_layout write segment size 2. Better mds-threshold 3. In above situation for a better clean split I will do this in future submission. Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>		2012-08-02 17:42:51 -04:00
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Kbuild
objio_osd.c	pnfs-obj: Better IO pattern in case of unaligned offset	2012-08-02 17:42:51 -04:00
objlayout.c	NFS: create common nfs_pgio_header for both read and write	2012-04-27 14:10:37 -04:00
objlayout.h
pnfs_osd_xdr_cli.c