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Compare the cost of allocating and freeing variable-sized regions using a bitmap, IDA and a Maple Tree. All implementations process the same randomly generated sequence of regions containing up to 32 entries, until the configured capacity is exhausted. The benchmark exercises monotonic allocation into an initially empty pool, followed by reverse-order freeing. It does not model fragmentation or interleaved allocation and freeing, nor does it isolate locking or RCU overhead. Allocation time includes the terminal failed request that detects exhaustion. Run the benchmark at several capacities to show how the approaches scale. Report allocation and free times separately because bitmap, IDA and Maple Tree removal have substantially different costs. On x86/kvm, the output example is: Start testing bitmap vs IDA vs Maple Tree region allocation memory: bitmap is exact; IDA and Maple Tree are lower bounds Type alloc (ns) free (ns) regions capacity memory (B) Bitmap 93457345 176151 60644 1000000 125000 Maple 11758660 12870146 60644 1000000 1552656 IDA 31066416 20870824 60644 1000000 134864 Bitmap 919119 17679 6032 100000 12504 Maple 1158193 1187140 6032 100000 154640 IDA 2759670 2116004 6032 100000 14288 Bitmap 17120 2043 613 10000 1256 Maple 116350 117537 613 10000 15888 IDA 243396 202654 613 10000 1872 Bitmap 1220 262 55 1000 128 Maple 12076 10106 55 1000 1552 IDA 25730 20875 55 1000 144 Bitmap 593 124 18 100 16 Maple 3599 4782 18 100 528 IDA 3266 1960 18 100 144 Bitmap 414 129 10 10 8 Maple 2143 1385 10 10 272 IDA 892 648 10 10 16 Region allocation benchmark complete Reported IDA and Maple Tree memory figures exclude slab overhead and transient allocations. The Maple Tree figure is additionally a lower-bound estimate that assumes fully occupied leaf nodes and excludes internal nodes. IDA has no region-allocation API, so each region is implemented as a sequence of single-ID allocations. The IDs remain contiguous because this benchmark fills an initially empty IDA monotonically. The benchmark is motivated by the discussion linked below about choosing the best data structure for the channel ID pool with the capacity of 2048 IDs for the nova GPU driver. Specifically for 2048 IDs the result is: Bitmap 5112 615 121 2048 256 Maple 78526 59592 121 2048 3344 IDA 165274 117761 121 2048 848 The benchmark accepts a list of up to 64 nonzero capacities to test. For example: insmod region_alloc_benchmark.ko capacities=1024,2048,4096,65536 The list may contain duplicate capacities. Each occurrence generates a new region-size sequence, which is useful for collecting statistical characteristics of the benchmark results. Link: https://lore.kernel.org/all/20260710-chid-maple-v1-1-4ee869055268@nvidia.com/ Tested-by: Eliot Courtney <ecourtney@nvidia.com> Reviewed-by: Eliot Courtney <ecourtney@nvidia.com> Signed-off-by: Yury Norov <ynorov@nvidia.com> |
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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 * AI Coding Assistant - LLMs and AI-powered development tools 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 AI Coding Assistant ------------------- CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and follow the AI coding assistants documentation before contributing to the Linux kernel: * Documentation/process/coding-assistants.rst This documentation contains essential requirements about licensing, attribution, and the Developer Certificate of Origin that all AI tools must comply with. 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