40d47c155e
In most cases blk_tracing is not active, but bfq_log_bfqq macro generate pid_str unconditionally, which result in significant overhead. ## Test modprobe null_blk echo bfq > /sys/block/nullb0/queue/scheduler fio --name=t --ioengine=libaio --direct=1 --filename=/dev/nullb0 \ --runtime=30 --time_based=1 --rw=write --iodepth=128 --bs=4k # Results | | baseline | w/ patch | gain | | iops | 113.19K | 126.42K | +11% | Acked-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Dmitry Monakhov <dmonakhov@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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.