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authorKiyoshi Ueda <k-ueda@ct.jp.nec.com>2009-06-22 05:12:27 -0400
committerAlasdair G Kergon <agk@redhat.com>2009-06-22 05:12:27 -0400
commit02ab823fd1a27d193bda06b74fdad685a20a3e5e (patch)
tree04b3db6e494f483fef34a55e487e88f6d7c585a5 /drivers/md/dm.c
parent2bd023452592e5f5cf90dd426cc39b7632b15b76 (diff)
dm mpath: add start_io and nr_bytes to path selectors
This patch makes two additions to the dm path selector interface for dynamic load balancers: o a new hook, start_io() o a new parameter 'nr_bytes' to select_path()/start_io()/end_io() to pass the size of the I/O start_io() is called when a target driver actually submits I/O to the selected path. Path selectors can use it to start accounting of the I/O. (e.g. counting the number of in-flight I/Os.) The start_io hook is based on the patch posted by Stefan Bader: https://www.redhat.com/archives/dm-devel/2005-October/msg00050.html nr_bytes, the size of the I/O, is so path selectors can take the size of the I/O into account when deciding which path to use. dm-service-time uses it to estimate service time, for example. (Added the nr_bytes member to dm_mpath_io instead of using existing details.bi_size, since request-based dm patch deletes it.) Signed-off-by: Stefan Bader <stefan.bader@canonical.com> Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md/dm.c')
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