766d61412e
Until the base value of the request service times gets finally computed for a bfq_queue, the inject limit does depend on the think-time state (short|long). The limit must be 0 or 1 if the think time is deemed, respectively, as short or long. However, such a check and possible limit update is performed only periodically, once per second. So, to make the injection mechanism much more reactive, this commit performs the update also every time the think-time state changes. In addition, in the following special case, this commit lets the inject limit of a bfq_queue bfqq remain equal to 1 even if bfqq's think time is short: bfqq's I/O is synchronized with that of some other queue, i.e., bfqq may receive new I/O only after the I/O of the other queue is completed. Keeping the inject limit to 1 allows the blocking I/O to be served while bfqq is in service. And this is very convenient both for bfqq and for the total throughput, as explained in detail in the comments in bfq_update_has_short_ttime(). Reported-by: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu> Tested-by: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> 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.