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Diffstat (limited to 'common/pmem.c')
| -rw-r--r-- | common/pmem.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/common/pmem.c b/common/pmem.c index e3e5e5c..5af17ac 100644 --- a/common/pmem.c +++ b/common/pmem.c @@ -1,3 +1,25 @@ +/** + * @file pmem.c + * Physical memory subsystem. Allocates physical memory pages, with support for + * different ordered pages, depending on the underlying architecture. + * + * Quick overview of the physical memory subsystem: Somewhere in RAM there + * exists a number of buckets, each with an n-tree representing different order + * pages and their status (used/free). When a lower-order memory page (i.e. + * smaller) is allocated, it blocks allocation of higher-order pages (i.e. + * larger) whose addresses would overlap. This is avoided by marking all + * higher-order pages as used in their respective buckets. + * + * This approach is reasonably efficient at handling the different possible page + * sizes, but requires that the caller maintains some data about page sizes, as + * the algorithm doesn't keep any of that information. Allocating a region of a + * certain page order and freeing it as another could easily be a + * source of difficult to track bugs. + * + * \todo More in depth documentation about the physical memory algorithms, + * unfortunately it is quite difficult to follow. + */ + #include <apos/mem_nodes.h> #include <apos/pmem.h> #include <apos/dmem.h> |