a393f33123
Buckets usually can't be discarded until the transaction that made them empty has been committed in the journal. Tracing has indicated that we're queuing the discard worker excessively, only for it to skip over many buckets that are still waiting on a journal commit, discarding only one or two buckets per iteration. We want to switch to only queuing the discard worker after a journal flush write, but there's an important optimization we need to preserve: if a bucket becomes empty and it was never committed in the journal while it was in use, we want to discard it and reuse it right away - since overwriting it before the previous writes are flushed from the device cache eans those writes only cost bus bandwidth. So, this patch implements a fast path for buckets that can be discarded right away. We need new locking between the two discard workers; the new list of buckets being discarded provides that locking. 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 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.