eaab9b5730
The time spent in io_schedule() and also the interrupt latency are
significant when submitting direct I/O to a UFS device. Hence this patch
that implements polling support. User space software can enable polling by
passing the RWF_HIPRI flag to the preadv2() system call or the
IORING_SETUP_IOPOLL flag to the io_uring interface.
Although the block layer supports to partition the tag space for
interrupt-based completions (HCTX_TYPE_DEFAULT) purposes and polling
(HCTX_TYPE_POLL), the choice has been made to use the same hardware queue
for both hctx types because partitioning the tag space would negatively
affect performance.
On my test setup this patch increases IOPS from 2736 to 22000 (8x) for the
following test:
for hipri in 0 1; do
fio --ioengine=io_uring --iodepth=1 --rw=randread \
--runtime=60 --time_based=1 --direct=1 --name=qd1 \
--filename=/dev/block/sda --ioscheduler=none --gtod_reduce=1 \
--norandommap --hipri=$hipri
done
Link: https://lore.kernel.org/r/20211203231950.193369-18-bvanassche@acm.org
Tested-by: Bean Huo <beanhuo@micron.com>
Reviewed-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.