1. 29 May, 2002 1 commit
    • Jens Axboe's avatar
      [PATCH] block plugging reworked/fixed · 8b1c3857
      Jens Axboe authored
      This implements what we discussed, basically just maintaing a plug list
      from the block layer as a direct parallel to the tq_disk task queue we
      had before.  blk_run_queues() now splices the blk_plug_list to avoid
      holding the blk_plug_lock across all the request_fn calls.
      8b1c3857
  2. 28 May, 2002 1 commit
    • Jens Axboe's avatar
      [PATCH] block plugging reworked · eba5b46c
      Jens Axboe authored
      This patch provides the ability for a block driver to signal it's too
      busy to receive more work and temporarily halt the request queue. In
      concept it's similar to the networking netif_{start,stop}_queue helpers.
      
      To do this cleanly, I've ripped out the old tq_disk task queue. Instead
      an internal list of plugged queues is maintained which will honor the
      current queue state (see QUEUE_FLAG_STOPPED bit). Execution of
      request_fn has been moved to tasklet context. blk_run_queues() provides
      similar functionality to the old run_task_queue(&tq_disk).
      
      Now, this only works at the request_fn level and not at the
      make_request_fn level. This is on purpose: drivers working at the
      make_request_fn level are essentially providing a piece of the block
      level infrastructure themselves. There are basically two reasons for
      doing make_request_fn style setups:
      
      o block remappers. start/stop functionality will be done at the target
        device in this case, which is the level that will signal hardware full
        (or continue) anyways.
      
      o drivers who wish to receive single entities of "buffers" and not
        merged requests etc. This could use the start/stop functionality. I'd
        suggest _still_ using a request_fn for these, but set the queue
        options so that no merging etc ever takes place. This has the added
        bonus of providing the usual request depletion throttling at the block
        level.
      eba5b46c
  3. 24 May, 2002 35 commits
  4. 23 May, 2002 3 commits