mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-07 17:27:11 -04:00
271557de7c
We really don't want to call cond_resched every single time we go through a loop in scrub -- there may be billions of records, and probing into the scheduler itself has overhead. Reduce this overhead by only calling cond_resched 10x per second; and add a counter so that we only check jiffies once every 1000 records or so. Surprisingly, this reduces scrub-only fstests runtime by about 2%. I used the bmapinflate xfs_db command to produce a billion-extent file and this stupid gadget reduced the scrub runtime by about 4%. From a stupid microbenchmark of calling these things 1 billion times, I estimate that cond_resched costs about 5.5ns per call; jiffes costs about 0.3ns per read; and fatal_signal_pending costs about 0.4ns per call. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
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 reStructuredText 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.