No description
- C 97%
- Assembly 1%
- Shell 0.6%
- Rust 0.5%
- Python 0.4%
- Other 0.3%
99430ab8b8
Introduce BPF kfuncs to conveniently access memcg data: - bpf_mem_cgroup_vm_events(), - bpf_mem_cgroup_memory_events(), - bpf_mem_cgroup_usage(), - bpf_mem_cgroup_page_state(), - bpf_mem_cgroup_flush_stats(). These functions are useful for implementing BPF OOM policies, but also can be used to accelerate access to the memcg data. Reading it through cgroupfs is much more expensive, roughly 5x, mostly because of the need to convert the data into the text and back. JP Kobryn: An experiment was setup to compare the performance of a program that uses the traditional method of reading memory.stat vs a program using the new kfuncs. The control program opens up the root memory.stat file and for 1M iterations reads, converts the string values to numeric data, then seeks back to the beginning. The experimental program sets up the requisite libbpf objects and for 1M iterations invokes a bpf program which uses the kfuncs to fetch all available stats for node_stat_item, memcg_stat_item, and vm_event_item types. The results showed a significant perf benefit on the experimental side, outperforming the control side by a margin of 93%. In kernel mode, elapsed time was reduced by 80%, while in user mode, over 99% of time was saved. control: elapsed time real 0m38.318s user 0m25.131s sys 0m13.070s experiment: elapsed time real 0m2.789s user 0m0.187s sys 0m2.512s control: perf data 33.43% a.out libc.so.6 [.] __vfscanf_internal 6.88% a.out [kernel.kallsyms] [k] vsnprintf 6.33% a.out libc.so.6 [.] _IO_fgets 5.51% a.out [kernel.kallsyms] [k] format_decode 4.31% a.out libc.so.6 [.] __GI_____strtoull_l_internal 3.78% a.out [kernel.kallsyms] [k] string 3.53% a.out [kernel.kallsyms] [k] number 2.71% a.out libc.so.6 [.] _IO_sputbackc 2.41% a.out [kernel.kallsyms] [k] strlen 1.98% a.out a.out [.] main 1.70% a.out libc.so.6 [.] _IO_getline_info 1.51% a.out libc.so.6 [.] __isoc99_sscanf 1.47% a.out [kernel.kallsyms] [k] memory_stat_format 1.47% a.out [kernel.kallsyms] [k] memcpy_orig 1.41% a.out [kernel.kallsyms] [k] seq_buf_printf experiment: perf data 10.55% memcgstat bpf_prog_..._query [k] bpf_prog_16aab2f19fa982a7_query 6.90% memcgstat [kernel.kallsyms] [k] memcg_page_state_output 3.55% memcgstat [kernel.kallsyms] [k] _raw_spin_lock 3.12% memcgstat [kernel.kallsyms] [k] memcg_events 2.87% memcgstat [kernel.kallsyms] [k] __memcg_slab_post_alloc_hook 2.73% memcgstat [kernel.kallsyms] [k] kmem_cache_free 2.70% memcgstat [kernel.kallsyms] [k] entry_SYSRETQ_unsafe_stack 2.25% memcgstat [kernel.kallsyms] [k] __memcg_slab_free_hook 2.06% memcgstat [kernel.kallsyms] [k] get_page_from_freelist Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Co-developed-by: JP Kobryn <inwardvessel@gmail.com> Signed-off-by: JP Kobryn <inwardvessel@gmail.com> Link: https://lore.kernel.org/r/20251223044156.208250-5-roman.gushchin@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.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 | ||
| .pylintrc | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. Quick Start ----------- * Report a bug: See Documentation/admin-guide/reporting-issues.rst * Get the latest kernel: https://kernel.org * Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst * Join the community: https://lore.kernel.org/ Essential Documentation ----------------------- All users should be familiar with: * Building requirements: Documentation/process/changes.rst * Code of Conduct: Documentation/process/code-of-conduct.rst * License: See COPYING Documentation can be built with make htmldocs or viewed online at: https://www.kernel.org/doc/html/latest/ Who Are You? ============ Find your role below: * New Kernel Developer - Getting started with kernel development * Academic Researcher - Studying kernel internals and architecture * Security Expert - Hardening and vulnerability analysis * Backport/Maintenance Engineer - Maintaining stable kernels * System Administrator - Configuring and troubleshooting * Maintainer - Leading subsystems and reviewing patches * Hardware Vendor - Writing drivers for new hardware * Distribution Maintainer - Packaging kernels for distros For Specific Users ================== New Kernel Developer -------------------- Welcome! Start your kernel development journey here: * Getting Started: Documentation/process/development-process.rst * Your First Patch: Documentation/process/submitting-patches.rst * Coding Style: Documentation/process/coding-style.rst * Build System: Documentation/kbuild/index.rst * Development Tools: Documentation/dev-tools/index.rst * Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst * Core APIs: Documentation/core-api/index.rst Academic Researcher ------------------- Explore the kernel's architecture and internals: * Researcher Guidelines: Documentation/process/researcher-guidelines.rst * Memory Management: Documentation/mm/index.rst * Scheduler: Documentation/scheduler/index.rst * Networking Stack: Documentation/networking/index.rst * Filesystems: Documentation/filesystems/index.rst * RCU (Read-Copy Update): Documentation/RCU/index.rst * Locking Primitives: Documentation/locking/index.rst * Power Management: Documentation/power/index.rst Security Expert --------------- Security documentation and hardening guides: * Security Documentation: Documentation/security/index.rst * LSM Development: Documentation/security/lsm-development.rst * Self Protection: Documentation/security/self-protection.rst * Reporting Vulnerabilities: Documentation/process/security-bugs.rst * CVE Procedures: Documentation/process/cve.rst * Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst * Security Features: Documentation/userspace-api/seccomp_filter.rst Backport/Maintenance Engineer ----------------------------- Maintain and stabilize kernel versions: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * Backporting Guide: Documentation/process/backporting.rst * Applying Patches: Documentation/process/applying-patches.rst * Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git for Maintainers: Documentation/maintainer/configure-git.rst System Administrator -------------------- Configure, tune, and troubleshoot Linux systems: * Admin Guide: Documentation/admin-guide/index.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst * Tracing/Debugging: Documentation/trace/index.rst * Performance Security: Documentation/admin-guide/perf-security.rst * Hardware Monitoring: Documentation/hwmon/index.rst Maintainer ---------- Lead kernel subsystems and manage contributions: * Maintainer Handbook: Documentation/maintainer/index.rst * Pull Requests: Documentation/maintainer/pull-requests.rst * Managing Patches: Documentation/maintainer/modifying-patches.rst * Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst * Development Process: Documentation/process/maintainer-handbooks.rst * Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git Configuration: Documentation/maintainer/configure-git.rst Hardware Vendor --------------- Write drivers and support new hardware: * Driver API Guide: Documentation/driver-api/index.rst * Driver Model: Documentation/driver-api/driver-model/driver.rst * Device Drivers: Documentation/driver-api/infrastructure.rst * Bus Types: Documentation/driver-api/driver-model/bus.rst * Device Tree Bindings: Documentation/devicetree/bindings/ * Power Management: Documentation/driver-api/pm/index.rst * DMA API: Documentation/core-api/dma-api.rst Distribution Maintainer ----------------------- Package and distribute the kernel: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * ABI Documentation: Documentation/ABI/README * Kernel Configuration: Documentation/kbuild/kconfig.rst * Module Signing: Documentation/admin-guide/module-signing.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst Communication and Support ========================= * Mailing Lists: https://lore.kernel.org/ * IRC: #kernelnewbies on irc.oftc.net * Bugzilla: https://bugzilla.kernel.org/ * MAINTAINERS file: Lists subsystem maintainers and mailing lists * Email Clients: Documentation/process/email-clients.rst