[ANNOUNCE] bfq-v3 for 2.6.39 and 3.0
Paolo Valente
here it is. There has been a fair amount of work behind the scenes
again. I have to thank mostly Arianna Avanzini, who also signed all the
patches (Mauro Andreolini helped us in several tasks too). As you can
see from the subject, we are not announcing just a port to 3.0, but a
new version of BFQ. It sports the following new features (see the
changelog in README.BFQ for more details):
. New improvements to the low-latency mechanisms, including a more
accurate criterion to distinguish between greedy-but-seeky and soft
real-time applications. Interactive applications now enjoy noticeably
lower latencies.
. Switch to the simpler one-request-dispatch-at-a-time scheme as in CFQ
. Cooperating-queues merging, ported from CFQ by Arianna Avanzini.
Queues of processes performing IO on interleaved, yet contiguous disk
zones are merged to boost the throughput. Some little optimizations to
get a more stable throughput have been added to the original port.
. Static fallback queue to deal with extreme OOM conditions, ported from
CFQ by Francesco Allertsen.
According to our tests on 2.6.39 and 3.0, none of these features is paid
with a loss of aggregate throughput with respect to BFQ-v2. As usually,
there is still room for improvement, because, e.g., interactive
applications happen occasionally to experience a quite higher latency
than the average. We are currently trying to debug these infrequent
events. In addition to the full patchset for 3.0, Arianna has prepared
incremental patches for any upgrade step (2.6.39-v2 -> 2.6.39-v3,
2.6.39-v2->3.0-v3, 2.6.39-v3->3.0-v3).
Stay tuned, because tests are running for bfq-v3-3.1-rc7 ...
Meanwhile, I hope you will enjoy this new version of BFQ,
Paolo