[PATCHv2 0/4] The Contiguous Memory Allocator
in [Kernel]
|
Prev: [PATCHv2 1/4] lib: rbtree: rb_root_init() function added
Next: [PATCHv2 4/4] arm: Added CMA to Aquila and Goni
From: Michal Nazarewicz on 26 Jul 2010 10:20 Hello everyone, The following patchset implements a Contiguous Memory Allocator. For those who have not yet stumbled across CMA an excerpt from documentation: The Contiguous Memory Allocator (CMA) is a framework, which allows setting up a machine-specific configuration for physically-contiguous memory management. Memory for devices is then allocated according to that configuration. The main role of the framework is not to allocate memory, but to parse and manage memory configurations, as well as to act as an in-between between device drivers and pluggable allocators. It is thus not tied to any memory allocation method or strategy. For more information please refer to the second patch from the patchset which contains the documentation. This is the second version of the patchset. All of the changes are concentrated in the second patch -- the other patches are almost identical. Major observable changes are: 1. The "cma_map" command line have been removed. In exchange, a SysFS entry has been created under kernel/mm/contiguous. The configuration strings passed to CMA are now called attributes in the documentation. The intended way of specifying the attributes is a cma_set_defaults() function called by platform initialisation code. "regions" attribute (the string specified by "cma" command line parameter) can be overwritten with command line parameter; the other attributes can be changed during run-time using the SysFS entries. (I still believe that the other attributes should have their own command line arguments as well but since they posed a lot of controversy (and many stopped reading after encountering them) "cma_map" have been removed.) 2. The behaviour of the "map" attribute has been modified slightly. Currently, if no rule matches given device it is assigned regions specified by the "asterisk" attribute. It is by default built from the region names given in "regions" attribute. This also means that if no "map" is specified all devices use all the regions specified in the "regions" attribute. This should be a handy default. 3. Devices can register private regions as well as regions that can be shared but are not reserved using standard CMA mechanisms. A private region has no name and can be accessed only by devices that have the pointer to it. Moreover, if device manages to run its code early enough it can register an "early region". An early region is one memory has not been reserved for. At one point, platform initialisation code reserves memory for all registered early regions and if this succeeds those regions are registered as normal regions that can be used with the standard API. This may be handy for devices that need some private region but don't want to worry about reserving it. 4. The way allocators are registered has changed. Currently, a cma_allocator_register() function is used for that purpose. Moreover, allocators are attached to regions the first time memory is registered from the region or when allocator is registered which means that allocators can be dynamic modules that are loaded after the kernel booted (of course, it won't be possible to allocate a chunk of memory from a region if allocator is not loaded). Index of new functions: +static inline dma_addr_t __must_check +cma_alloc_from(const char *regions, size_t size, dma_addr_t alignment) +static inline int +cma_info_about(struct cma_info *info, const const char *regions) +int __must_check cma_region_register(struct cma_region *reg); +dma_addr_t __must_check +cma_alloc_from_region(struct cma_region *reg, + size_t size, dma_addr_t alignment); +static inline dma_addr_t __must_check +cma_alloc_from(const char *regions, + size_t size, dma_addr_t alignment); +int cma_allocator_register(struct cma_allocator *alloc); The patches in the patchset include: Michal Nazarewicz (4): lib: rbtree: rb_root_init() function added The rb_root_init() function initialises an RB tree with a single node placed in the root. This is more convenient then initialising an empty tree and then adding an element. mm: cma: Contiguous Memory Allocator added This patch is the main patchset that implements the CMA framework including the best-fit allocator. It also adds a documentation. mm: cma: Test device and application added This patch adds a misc device that works as a proxy to the CMA framework and a simple testing application. This lets one test the whole framework from user space as well as reply an recorded allocate/free sequence. arm: Added CMA to Aquila and Goni This patch adds the CMA platform initialisation code to two ARM platforms. It serves as an example of how this is achieved. Documentation/00-INDEX | 2 + .../ABI/testing/sysfs-kernel-mm-contiguous | 9 + Documentation/contiguous-memory.txt | 646 +++++++++++ Documentation/kernel-parameters.txt | 4 + arch/arm/mach-s5pv210/mach-aquila.c | 13 + arch/arm/mach-s5pv210/mach-goni.c | 13 + drivers/misc/Kconfig | 8 + drivers/misc/Makefile | 1 + drivers/misc/cma-dev.c | 184 +++ include/linux/cma.h | 475 ++++++++ include/linux/rbtree.h | 11 + mm/Kconfig | 34 + mm/Makefile | 3 + mm/cma-best-fit.c | 407 +++++++ mm/cma.c | 1170 ++++++++++++++++++++ tools/cma/cma-test.c | 373 +++++++ 16 files changed, 3353 insertions(+), 0 deletions(-) create mode 100644 Documentation/ABI/testing/sysfs-kernel-mm-contiguous create mode 100644 Documentation/contiguous-memory.txt create mode 100644 drivers/misc/cma-dev.c create mode 100644 include/linux/cma.h create mode 100644 mm/cma-best-fit.c create mode 100644 mm/cma.c create mode 100644 tools/cma/cma-test.c -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |