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Linux kernel source tree
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The slot cache for freeing path is mostly for reducing the overhead of si->lock. As we have basically eliminated the si->lock usage for freeing path, it can be removed. This helps simplify the code, and avoids swap entries from being hold in cache upon freeing. The delayed freeing of entries have been causing trouble for further optimizations for zswap [1] and in theory will also cause more fragmentation, and extra overhead. Test with build linux kernel showed both performance and fragmentation is better without the cache: tiem make -j96 / 768M memcg, 4K pages, 10G ZRAM, avg of 4 test run:: Before: Sys time: 36047.78, Real time: 472.43 After: (-7.6% sys time, -7.3% real time) Sys time: 33314.76, Real time: 437.67 time make -j96 / 1152M memcg, 64K mTHP, 10G ZRAM, avg of 4 test run: Before: Sys time: 46859.04, Real time: 562.63 hugepages-64kB/stats/swpout: 1783392 hugepages-64kB/stats/swpout_fallback: 240875 After: (-23.3% sys time, -21.3% real time) Sys time: 35958.87, Real time: 442.69 hugepages-64kB/stats/swpout: 1866267 hugepages-64kB/stats/swpout_fallback: 158330 Sequential SWAP should be also slightly faster, tests didn't show a measurable difference though, at least no regression: Swapin 4G zero page on ZRAM (time in us): Before (avg. 1923756) |
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| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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 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.