This patch set adds support in block & elevator layers for handling urgent requests. In order to decrease the latency of a prioritized request (such as READ requests) we might want to stop the transmission of a current "low priority" request in order to handle the "high priority" one. The urgency of the request is decided by the block layer I/O scheduler. When the block layer notifies the underlying device driver (eMMC for example) of an urgent request, the device driver might decide to stop the current request transmission. The remainder of the stopped request will be re-inserted back to the scheduler, to be re-scheduled after handling the urgent request. The above is implemented in the block layer by 2 callbacks of the queue: - urgent_request_fn() - This callback is registered by the underlying device driver and is called instead of the existing requst_fn() callback to handle urgent requests. - elevator_is_urgent_fn() - This callback is registered by the current I/O scheduler. If present it's used by the block layer to query the scheduler of an urgent request presence. NOTE: If one of the above callbacks is not registered, this code pass will never be activated. Tatyana Brokhman (2): block: Add support for reinsert a dispatched req block: Add API for urgent request handling block/blk-core.c | 70 ++++++++++++++++++++++++++++++++++++++++++++- block/blk-settings.c | 12 ++++++++ block/blk.h | 11 +++++++ block/elevator.c | 40 ++++++++++++++++++++++++++ include/linux/blkdev.h | 6 ++++ include/linux/elevator.h | 7 ++++ 6 files changed, 144 insertions(+), 2 deletions(-) -- 1.7.6 -- QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. Is a member of Code Aurora Forum, hosted by the Linux Foundation -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
