Unused slabs which get recycled are no longer reinitialized from scratch if their chunk size matches what the allocator needed. If the chunk size matches, the list of available chunks is left unchanged, and just the various counters are reset.
Added __get_slab_stats() function.
Added support for global __slab_purge_threshold tuning variable.
Added a short test program for the slab allocator.
The malloc-test program was linked against the wrong object file in GNUmakefile.68k. Fixed.
Added more consistency checking to the slab allocator, which is built if DEBUG is defined in "stdlib_slab.c".
Memory allocations are no longer guaranteed to be aligned to 64 bit word boundaries. In fact, this has not even worked reliably in the past 10 years.
Memory allocation request sizes are now rounded to multiples of 32 bit words (the size of an address pointer) instead to the size of a 64 bit word.
Reduced the memory footprint of the memory allocation management data structures by reusing the most significant bit of the memory allocation size. This allows many more allocations to fit into the 32 byte chunk slabs, but limits the maximum memory allocation size to a little less than 2 GBytes.
Added integer overflow checks to the memory management code.
Reduced the memory management overhead further. This cuts an additional 8 bytes per allocation, unless neither the slab allocator nor memory pools are available. With this reduction the slab allocator is able to use 16 byte chunks, which cover memory allocation requests of 1..8 bytes.
Fixed a bug caused by returning an allocation back to a slab which passed the wrong pointer.
If the first slab in the list of slabs which share the same chunk size has no more room, it means that all other slabs following it have no room either. This speeds up the test to find a slab with free space, which can now abort and directly proceed to allocate memory for a new slab.
If an empty slab's decay count hits zero, it is moved to the front of the empty slab list to be reclaimed more quickly.
Allocations made from the slab now carry a pointer back to the slab which they are a part of. This speeds up deallocation but has the downside of making the smallest usable slab chunk size 64 bytes, which is double what used to be the minimum before.
The maximum slab size is now 2^17 bytes (= 131072). If you request a slab size larger than this, you will get slab sizes of 131072 bytes instead.
Enabling the memory management debugging code no longer produces compiler errors.
Added a slab allocator which replaces the use of memory pools or the plain AllocMem() operations, respectively. In order to activate the slab allocator, choose a slab size (e.g. 2048 bytes or 4096 bytes) and declare a global variable like this:
ULONG __slab_max_size = 2048;
Memory allocations smaller than the slab size will be made from "slabs", i.e. large chunks of memory of the given size. Larger allocations will be managed separately.
A slab-allocator can now be used as the back-end for all memory allocations by setting __slab_max_size to a value > 0. This controls the slab size used for allocations and should be a power of 2, such as 2048 or 4096 bytes.
This change still needs testing.
- Replaced ISO Latin 1 code #160 with a plain blank space (ASCII code #32) where necessary
git-svn-id: file:///Users/olsen/Code/migration-svn-zu-git/logical-line-staging/clib2/trunk@15305 87f5fb63-7c3d-0410-a384-fd976d0f7a62
request to allocate 0 bytes as an error, returning NULL. They all
return a pointer sized memory chunk (= four bytes) initialized to
NULL (= 0) instead.
- The alloca() implementation which allocates memory from the system
rather than the local stack frame is thread-safe now. It also
interacts with the realloc(), calloc(), free() and malloc() functions
in that the alloca() cleanup routine is called once alloca() has
done its job. If all the memory allocated through alloca() has been
released no further calls to the cleanup function will be made.
- In the thread-safe library, realloc() permitted two different overlapping
calls to succeed in trying to reallocate the same chunk of memory due to
a race condition. Fixed.
git-svn-id: file:///Users/olsen/Code/migration-svn-zu-git/logical-line-staging/clib2/trunk@15070 87f5fb63-7c3d-0410-a384-fd976d0f7a62
was still wrongish for the OS4 library. So I had to change
it *again*. Which probably means that the 68k library will
need further changes...
git-svn-id: file:///Users/olsen/Code/migration-svn-zu-git/logical-line-staging/clib2/trunk@14894 87f5fb63-7c3d-0410-a384-fd976d0f7a62
- Dropped unused stub code which is now redundant because of
the constructor/destructor mechanism.
git-svn-id: file:///Users/olsen/Code/migration-svn-zu-git/logical-line-staging/clib2/trunk@14891 87f5fb63-7c3d-0410-a384-fd976d0f7a62
