Messages in this thread | | | Date | Wed, 26 Jan 2000 16:40:27 +0100 | From | Jens Axboe <> | Subject | RFC: request merges with active heads |
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Hi,
Currently we have a problem merging requests properly for low level drivers that have active heads. Consider this:
64KB write comes in. The first block (assuming 2048 sector size here, but that is not relevant) gets a new request. When __make_request is invoked a second time it finds a current_request but skips this one, because the driver might be working on it right now.
So instead of one nice request, the low level driver gets two. One for the first block and a second with the rest merged. I propose that we add a RQ_STARTED flag or similar to let ll_rw_blk determine whether it is safe to merge with the current_request for drivers that have an active request head.
Comments?
-- * Jens Axboe <axboe@suse.de> * Linux CD-ROM Maintainer * http://www.kernel.dk
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