kheap -...

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Unformatted text preview: #include <types.h> #include <lib.h> #include <vm.h> #include <machine/spl.h> static void fill_deadbeef(void *vptr, size_t len) { u_int32_t *ptr = vptr; size_t i; for (i=0; i<len/sizeof(u_int32_t); i++) { ptr[i] = 0xdeadbeef; } } //////////////////////////////////////////////////////////// // // Pool-based subpage allocator. // // It works like this: // // We allocate one page at a time and fill it with objects of size k, // for various k. Each page has its own freelist, maintained by a // linked list in the first word of each object. Each page also has a // freecount, so we know when the page is completely free and can // release it. // // No assumptions are made about the sizes k; they need not be // powers of two. Note, however, that malloc must always return // pointers aligned to the maximum alignment requirements of the // platform; thus block sizes must at least be multiples of 4, // preferably 8. They must also be at least sizeof(struct // freelist). It is only worth defining an additional block size if // more blocks would fit on a page than with the existing block // sizes, and large numbers of items of the new size are allocated. // // The free counts and addresses of the pages are maintained in // another list. Maintaining this table is a nuisance, because it // cannot recursively use the subpage allocator. (We could probably // make that work, but it would be painful.) // #undef SLOW /* consistency checks */ #undef SLOWER /* lots of consistency checks */ //////////////////////////////////////// #if PAGE_SIZE == 4096 #define NSIZES 8 static const size_t sizes[NSIZES] = { 16, 32, 64, 128, 256, 512, 1024, 2048 }; #define SMALLEST_SUBPAGE_SIZE 16 #define LARGEST_SUBPAGE_SIZE 2048 #elif PAGE_SIZE == 8192 #error "No support for 8k pages" #else #error "Odd page size" #endif //////////////////////////////////////// struct freelist { struct freelist *next; }; struct pageref { struct pageref *next_samesize; struct pageref *next_all; vaddr_t pageaddr_and_blocktype; u_int16_t freelist_offset; u_int16_t nfree; }; #define INVALID_OFFSET (0xffff) #define PR_PAGEADDR(pr) ((pr)->pageaddr_and_blocktype & PAGE_FRAME) #define PR_BLOCKTYPE(pr) ((pr)->pageaddr_and_blocktype & ~PAGE_FRAME) #define MKPAB(pa, blk) (((pa)&PAGE_FRAME) | ((blk) & ~PAGE_FRAME)) //////////////////////////////////////// /* * This is cheesy. * * The problem is not that it's wasteful - we can only allocate whole * pages of pageref structures at a time anyway. The problem is that * we really ought to be able to have more than one of these pages. * * However, for the time being, one page worth of pagerefs gives us * 256 pagerefs; this lets us manage 256 * 4k = 1M of kernel heap....
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This note was uploaded on 11/10/2009 for the course CS 536 taught by Professor Lums during the Spring '09 term at Indiana.

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kheap -...

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