mirror of
https://github.com/torvalds/linux.git
synced 2026-07-29 18:51:21 +02:00
Linux kernel source tree
bb317f00b9
Patch series "mm/compaction: allow more aggressive proactive compaction", v4. Our goal is to keep memory usage of a VM low on the host. For that reason, we use free page reporting which by default reports free pages of order 9 and larger to the host to be freed. The feature works well only if the memory in the guest is not fragmented below pages of order 9. Proactive compaction can be reused to achieve defragmentation after some parameter tweaking. When the fragmentation score (lower is better) gets larger than the high watermark, proactive compaction kicks in. Compaction stops when the score goes below the low watermark (or no progress is made and backoff kicks in). Let's define the difference between high and low watermarks as leeway. Before these changes, the minimum possible value for low watermark was 5 and the leeway was hardcoded to 10 (so minimum possible value for high watermark was 15). To test this, I created a VM with 19GB of memory and free page reporting enabled. The VM was ~idle. I meassured the memory usage from inside the guest (/proc/meminfo) and from the host (provided by the hypervisor). Before: https://drive.google.com/file/d/1Xw23lRry_PgEH3f6QRnSGvoHh2u9UHyI/view?usp=sharing After: https://drive.google.com/file/d/1wMhpIzepx6t44F70yCPA50n1S5V2AT-a/view?usp=sharing This patch (of 2): Previously a min cap of 5 has been set in the commit introducing proactive compaction. This was to make sure users don't hurt themselves by setting the proactiveness to 100 and making their system unresponsive. But the compaction mechanism has a backoff mechanism that will sleep for 30s if no progress is made, so I don't see a significant risk here. My system (19GB of memory) has been perfectly fine with both watermarks hardcoded to 0. Link: https://lkml.kernel.org/r/20250404111103.1994507-1-mclapinski@google.com Link: https://lkml.kernel.org/r/20250404111103.1994507-2-mclapinski@google.com Signed-off-by: Michal Clapinski <mclapinski@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
||
|---|---|---|
| arch | ||
| 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.