adfe9357c3
Freeing key cache items is a multi stage process; we need to wait for an SRCU grace period to elapse, and we handle this ourselves - partially to avoid callback overhead, but primarily so that when allocating we can first allocate from the freed items waiting for an SRCU grace period. Previously, the shrinker was counting the items on the 'waiting for SRCU grace period' lists as items being scanned, but this meant that too many items waiting for an SRCU grace period could prevent it from doing any work at all. After this, we're seeing that items skipped due to the accessed bit are the main cause of the shrinker not making any progress, and we actually want the key cache shrinker to run quite aggressively because reclaimed items will still generally be found (more compactly) in the btree node cache - so we also tweak the shrinker to not count those against nr_to_scan. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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.