f733164829
blk-cgroup has been using blkg_rwstat to track basic IO stats.
Unfortunately, reading recursive stats scales badly as itinvolves
walking all descendants. On systems with a huge number of cgroups
(dead or alive), this can lead to substantial CPU cost when reading IO
stats.
This patch reimplements basic IO stats using cgroup rstat which uses
more memory but makes recursive stat reading O(# descendants which
have been active since last reading) instead of O(# descendants).
* blk-cgroup core no longer uses sync/async stats. Introduce new stat
enums - BLKG_IOSTAT_{READ|WRITE|DISCARD}.
* Add blkg_iostat[_set] which encapsulates byte and io stats, last
values for propagation delta calculation and u64_stats_sync for
correctness on 32bit archs.
* Update the new percpu stat counters directly and implement
blkcg_rstat_flush() to implement propagation.
* blkg_print_stat() can now bring the stats up to date by calling
cgroup_rstat_flush() and print them instead of directly summing up
all descendants.
* It now allocates 96 bytes per cpu. It used to be 40 bytes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Dan Schatzberg <dschatzberg@fb.com>
Cc: Daniel Xu <dlxu@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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|---|---|---|
| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
README
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.