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authorBenjamin Marzinski <bmarzins@redhat.com>2007-08-23 20:19:05 +0200
committerSteven Whitehouse <swhiteho@redhat.com>2007-10-10 09:55:48 +0200
commitc4f68a130fc1795e4a75ec5bdaf9e85d86c22419 (patch)
tree37251ae5634d4b73b5224e3e8679f92472de0ebe /block/as-iosched.c
parent[GFS2] panic after can't parse mount arguments (diff)
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[GFS2] delay glock demote for a minimum hold time
When a lot of IO, with some distributed mmap IO, is run on a GFS2 filesystem in a cluster, it will deadlock. The reason is that do_no_page() will repeatedly call gfs2_sharewrite_nopage(), because each node keeps giving up the glock too early, and is forced to call unmap_mapping_range(). This bumps the mapping->truncate_count sequence count, forcing do_no_page() to retry. This patch institutes a minimum glock hold time a tenth a second. This insures that even in heavy contention cases, the node has enough time to get some useful work done before it gives up the glock. A second issue is that when gfs2_glock_dq() is called from within a page fault to demote a lock, and the associated page needs to be written out, it will try to acqire a lock on it, but it has already been locked at a higher level. This patch puts makes gfs2_glock_dq() use the work queue as well, to avoid this issue. This is the same patch as Steve Whitehouse originally proposed to fix this issue, execpt that gfs2_glock_dq() now grabs a reference to the glock before it queues up the work on it. Signed-off-by: Benjamin E. Marzinski <bmarzins@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Diffstat (limited to 'block/as-iosched.c')
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