blk-cgroup: Initialize ioc->cgroup_changed at ioc creation time
Vivek Goyal [Mon, 23 May 2011 17:35:04 +0000 (19:35 +0200)]
If we don't explicitly initialize it to zero, CFQ might think that
cgroup of ioc has changed and it generates lots of unnecessary calls
to call_for_each_cic(changed_cgroup). Fix it.

cfq_get_io_context()
  cfq_ioc_set_cgroup()
     call_for_each_cic(ioc, changed_cgroup)

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

block/blk-ioc.c

index b791022..c898049 100644 (file)
@@ -96,6 +96,9 @@ struct io_context *alloc_io_context(gfp_t gfp_flags, int node)
                INIT_RADIX_TREE(&ret->radix_root, GFP_ATOMIC | __GFP_HIGH);
                INIT_HLIST_HEAD(&ret->cic_list);
                ret->ioc_data = NULL;
+#if defined(CONFIG_BLK_CGROUP) || defined(CONFIG_BLK_CGROUP_MODULE)
+               ret->cgroup_changed = 0;
+#endif
        }
 
        return ret;