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authorOlaf Kirch <okir@lst.de>2008-04-29 13:46:53 -0700
committerRoland Dreier <rolandd@cisco.com>2008-04-29 13:46:53 -0700
commitbbdc2821db041fb07ffa52e4a0e1ebb5410790e9 (patch)
tree1a0757409c89c6236d9c0ffa1eb0f5a63faa2527 /drivers/infiniband
parentd227fa7288adebe5ba37fa8e4a589c977d4e4a34 (diff)
mlx4_core: Avoid recycling old FMR R_Keys too soon
When a FMR is unmapped, mlx4 resets the map count to 0, and clears the upper part of the R_Key which is used as the sequence counter. This poses a problem for RDS, which uses ib_fmr_unmap as a fence operation. RDS assumes that after issuing an unmap, the old R_Keys will be invalid for a "reasonable" period of time. For instance, Oracle processes uses shared memory buffers allocated from a pool of buffers. When a process dies, we want to reclaim these buffers -- but we must make sure there are no pending RDMA operations to/from those buffers. The only way to achieve that is by using unmap and sync the TPT. However, when the sequence count is reset on unmap, there is a high likelihood that a new mapping will be given the same R_Key that was issued a few milliseconds ago. To prevent this, don't reset the sequence count when unmapping a FMR. Signed-off-by: Olaf Kirch <olaf.kirch@oracle.com> Signed-off-by: Roland Dreier <rolandd@cisco.com>
Diffstat (limited to 'drivers/infiniband')
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