Change Details

Change the usage of the pool field in vm_page structs. Currently, every page belongs to a pool, and the pool field identifies that pool. With this change: 1. Free memory blocks are only have valid pool fields when they are the first page in a block in a buddy queue. Otherwise, the value of pool is VM_NFREEPOOL. 2. Memory allocated in power-of-two sized blocks, by vm_phys_alloc_freelist_pages or vm_phys_alloc_pages, have only the first page of the block with a valid pool field; the others have VM_NFREEPOOL as their pool field. The function vm_phys_free_pages frees such blocks and restores the first page field to VM_NFREEPOOL. 3. Memory allocated as a number of pages by vm_phys_alloc_npages has no page marked with the pool value. The memory is freed by vm_phys_free_npages, and that caller provides the pool value as a parameter. Where the pool value is needed, in vm_page_free_toq, it has been supplied by the function that called uma_zalloc to allocate it from the pgcache. 4. Memory allocated as a number of pages, by vm_phys_alloc_contig, has every page marked with the pool value. Such memory can be freed all at once with vm_phys_free_contig, or one page at a time with vm_phys_free_pages(m, 0). 4. A range of pages with all pool fields set to VM_NFREEPOOL can be freed with vm_phys_enqueue_contig, which passes the pool value as a parameter. The function vm_page_startup uses it to initialize the buddy queues, and vm_reserv_break uses it to return to the buddy queues unused pages from a broken reservation.

Change the usage of the pool field in vm_page structs. Currently, every page belongs to a pool, and the pool field identifies that pool. With this change: 1. Free memory blocks are only have valid pool fields when they are the first page in a block in a buddy queue. Otherwise, the value of pool is VM_NFREEPOOL. 2. Memory allocated in power-of-two sized blocks, by vm_phys_alloc_freelist_pages or vm_phys_alloc_pages, have only the first page of the block with a valid pool field; the others have VM_NFREEPOOL as their pool field. The function vm_phys_free_pages frees such blocks and restores the first page field to VM_NFREEPOOL. 3. Memory allocated as a number of pages by vm_phys_alloc_npages has no page marked with the pool value. The memory is freed by vm_phys_free_npages, and that caller provides the pool value as a parameter. Where the pool value is needed, in vm_page_free_toq, it has been supplied by the function that called uma_zalloc to allocate it from the pgcache. 4. Memory allocated as a number of pages, by vm_phys_alloc_contig, has only the first page marked with the pool value. Such memory can be freed all at once with vm_phys_free_contig, or one page at a time with vm_phys_free_pages(m, 0). 4. A range of pages with all pool fields set to VM_NFREEPOOL can be freed with vm_phys_enqueue_contig, which passes the pool value as a parameter. The function vm_page_startup uses it to initialize the buddy queues, and vm_reserv_break uses it to return to the buddy queues unused pages from a broken reservation. 5. vm_phys_free_pages no longer immediately frees pages. Each domain maintains a range of pages waiting to be freed; when vm_phys_free_pages finds that the memory it is to free can extend that range, it does so. When it cannot, free_contig frees all that memory at once, and a new deferred free range is created. The deferred free range is flushed before any allocation from its domain. This all allows a pool to be guessed; if the pages allocated with alloc_contig are freed from first page to last, then the pool from the first page will be used to free all of them to that pool. If pages from that allocation are freed in a random order, though, some will end up in the default pool regardless of the pool from which they originally came.

Change the usage of the pool field in vm_page structs. Currently, every page belongs to a pool, and the pool field identifies that pool. With this change: 1. Free memory blocks are only have valid pool fields when they are the first page in a block in a buddy queue. Otherwise, the value of pool is VM_NFREEPOOL. 2. Memory allocated in power-of-two sized blocks, by vm_phys_alloc_freelist_pages or vm_phys_alloc_pages, have only the first page of the block with a valid pool field; the others have VM_NFREEPOOL as their pool field. The function vm_phys_free_pages frees such blocks and restores the first page field to VM_NFREEPOOL. 3. Memory allocated as a number of pages by vm_phys_alloc_npages has no page marked with the pool value. The memory is freed by vm_phys_free_npages, and that caller provides the pool value as a parameter. Where the pool value is needed, in vm_page_free_toq, it has been supplied by the function that called uma_zalloc to allocate it from the pgcache. 4. Memory allocated as a number of pages, by vm_phys_alloc_contig, has everyonly the first page marked with the pool value. Such memory can be freed all at once with vm_phys_free_contig, or one page at a time with vm_phys_free_pages(m, 0). 4. A range of pages with all pool fields set to VM_NFREEPOOL can be freed with vm_phys_enqueue_contig, which passes the pool value as a parameter. The function vm_page_startup uses it to initialize the buddy queues, and vm_reserv_break uses it to return to the buddy queues unused pages from a broken reservation. 5. vm_phys_free_pages no longer immediately frees pages. Each domain maintains a range of pages waiting to be freed; when vm_phys_free_pages finds that the memory it is to free can extend that range, it does so. When it cannot, free_contig frees all that memory at once, and a new deferred free range is created. The deferred free range is flushed before any allocation from its domain. This all allows a pool to be guessed; if the pages allocated with alloc_contig are freed from first page to last, then the pool from the first page will be used to free all of them to that pool. If pages from that allocation are freed in a random order, though, some will end up in the default pool regardless of the pool from which they originally came.