tree 450d0f92533184d85ac00ab1625460fe0be4cda7
parent 1afba0451c83cbff622a08f2d86fbb2e680dfd5f
author Jens Axboe <jens.axboe@oracle.com> 1177072070 +0200
committer Jens Axboe <axboe@nelson.home.kernel.dk> 1177916481 +0200

cfq-iosched: rework the whole round-robin list concept

Drawing on some inspiration from the CFS CPU scheduler design, overhaul
the pending cfq_queue concept list management. Currently CFQ uses a
doubly linked list per priority level for sorting and service uses.
Kill those lists and maintain an rbtree of cfq_queue's, sorted by when
to service them.

This unfortunately means that the ionice levels aren't as strong
anymore, will work on improving those later. We only scale the slice
time now, not the number of times we service. This means that latency
is better (for all priority levels), but that the distinction between
the highest and lower levels aren't as big.

The diffstat speaks for itself.

 cfq-iosched.c |  363 +++++++++++++++++---------------------------------
 1 file changed, 125 insertions(+), 238 deletions(-)

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>