This patch is to add the basic support of QoS on bdev.
Including two major functionalities:
1. The QoS rate limiting algorithm:
a. New IO will be always queued first also under
the no memory condition
b. Start the QoS IO operation based on the limit
c. A poller started in each millisecond to reset
the rate limit and send new IOs down
d. The rate limit is based on the millisecond and
converted from user configurable IOsPerSecond
2. The Master Thread management:
a. Add a per bdev channel_count
b. Whenever QoS is enabled on bdev, if QoS bdev
channel is not created, create the QoS bdev
channel and assign the QoS thread
c. When new IOs coming from different channels
(threads), pass the IOs to the QoS bdev channel
through the thread event
d. When the IOs are completed from the QoS bdev
channel, pass the IOs back to its orignal
channel(thread)
e. Destroy the QoS bdev channel when it is the
last bdev channel for this bdev. Defer the
destruction if current thread is not QoS thread
Change-Id: Ie4444551d7c3c7de52f6513c9db926628796adb4
Signed-off-by: GangCao <gang.cao@intel.com>
Reviewed-on: https://review.gerrithub.io/393136
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
a2142f3a33