On 3/10/23 12:04?PM, Pavel Begunkov wrote:
io_uring extensively uses task_work, but when a task is waiting
for multiple CQEs it causes lots of rescheduling. This series
is an attempt to optimise it and be a base for future improvements.
For some zc network tests eventually waiting for a portion of
buffers I've got 10x descrease in the number of context switches,
which reduced the CPU consumption more than twice (17% -> 8%).
It also helps storage cases, while running fio/t/io_uring against
a low performant drive it got 2x descrease of the number of context
switches for QD8 and ~4 times for QD32.
Not for inclusion yet, I want to add an optimisation for when
waiting for 1 CQE.
Ran this on the usual peak benchmark, using IRQ. IOPS is around ~70M for
that, and I see context rates of around 8.1-8.3M/sec with the current
kernel.