Hi all, We need to throttle the O_DIRECT IO on data and metadata device of a dm-thin pool and encounter some problems. If we set the limitation on the root blkcg, the throttle works. If we set the limitation on a child blkcg, the throttle doesn't work well. The reason why the throttle doesn't work is that dm-thin defers the process of bio when the physical block of bio has not been allocated. The bio will be submitted by the pool worker, and the blkcg of the bio will be the blkcg of the pool worker, namely, the root blkcg instead of the blkcg of the original IO thread. We only set a limitation on the blkcg of the original IO thread, so the blk-throttle doesn't work well. In order to handle the situation, we add a "keep_bio_blkcg" feature to dm-thin. If the feature is enabled, the original blkcg of bio will be saved at thin_map() and will be used during blk-throttle. Tao Hou Tao (4): dm thin: add a pool feature "keep_bio_blkcg" dm thin: parse "keep_bio_blkcg" from userspace tools dm thin: show the enabled status of keep_bio_blkcg feature dm thin: associate bio with current task if keep_bio_blkcg is enabled drivers/md/dm-thin.c | 26 ++++++++++++++++++++++++-- drivers/md/dm-thin.h | 17 +++++++++++++++++ 2 files changed, 41 insertions(+), 2 deletions(-) create mode 100644 drivers/md/dm-thin.h -- 2.5.0 -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
