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authorChen, Kenneth W <kenneth.w.chen@intel.com>2006-12-13 00:34:36 -0800
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-13 09:05:50 -0800
commite61c90188b9956edae1105eef361d8981a352fcd (patch)
tree7de9cc41910c55e32aba0f8cc07f73923b7cb515 /Documentation/stallion.txt
parent7e913c53609d5e8374f55d6f29c0bcd6650a2362 (diff)
[PATCH] optimize o_direct on block devices
Implement block device specific .direct_IO method instead of going through generic direct_io_worker for block device. direct_io_worker() is fairly complex because it needs to handle O_DIRECT on file system, where it needs to perform block allocation, hole detection, extents file on write, and tons of other corner cases. The end result is that it takes tons of CPU time to submit an I/O. For block device, the block allocation is much simpler and a tight triple loop can be written to iterate each iovec and each page within the iovec in order to construct/prepare bio structure and then subsequently submit it to the block layer. This significantly speeds up O_D on block device. [akpm@osdl.org: small speedup] Signed-off-by: Ken Chen <kenneth.w.chen@intel.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Zach Brown <zach.brown@oracle.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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