函数源码 |
Source File:mm\zsmalloc.c |
Create Date:2022-07-27 18:03:19 |
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2390 2391 2392 2393 2394 2395 2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 2422 2423 2424 2425 2426 2427 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463 2464 2465 2466 2467 2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491 2492 2493 2494 2495 2496 2497 2498 2499 2500 2501 2502 2503 2504 2505 2506 2507 2508 2509 2510 2511 2512 2513 | /** * zs_create_pool - Creates an allocation pool to work from. * @name: pool name to be created * * This function must be called before anything when using * the zsmalloc allocator. * * On success, a pointer to the newly created pool is returned, * otherwise NULL. */ struct zs_pool *zs_create_pool( const char *name) { int i; struct zs_pool *pool; struct size_class *prev_class = NULL; pool = kzalloc( sizeof (*pool), GFP_KERNEL); if (!pool) return NULL; init_deferred_free(pool); pool->name = kstrdup(name, GFP_KERNEL); if (!pool->name) goto err; #ifdef CONFIG_COMPACTION init_waitqueue_head(&pool->migration_wait); #endif if (create_cache(pool)) goto err; /* * Iterate reversely, because, size of size_class that we want to use * for merging should be larger or equal to current size. */ for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) { int size; int pages_per_zspage; int objs_per_zspage; struct size_class * class ; int fullness = 0; size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA; if (size > ZS_MAX_ALLOC_SIZE) size = ZS_MAX_ALLOC_SIZE; pages_per_zspage = get_pages_per_zspage(size); objs_per_zspage = pages_per_zspage * PAGE_SIZE / size; /* * We iterate from biggest down to smallest classes, * so huge_class_size holds the size of the first huge * class. Any object bigger than or equal to that will * endup in the huge class. */ if (pages_per_zspage != 1 && objs_per_zspage != 1 && !huge_class_size) { huge_class_size = size; /* * The object uses ZS_HANDLE_SIZE bytes to store the * handle. We need to subtract it, because zs_malloc() * unconditionally adds handle size before it performs * size class search - so object may be smaller than * huge class size, yet it still can end up in the huge * class because it grows by ZS_HANDLE_SIZE extra bytes * right before class lookup. */ huge_class_size -= (ZS_HANDLE_SIZE - 1); } /* * size_class is used for normal zsmalloc operation such * as alloc/free for that size. Although it is natural that we * have one size_class for each size, there is a chance that we * can get more memory utilization if we use one size_class for * many different sizes whose size_class have same * characteristics. So, we makes size_class point to * previous size_class if possible. */ if (prev_class) { if (can_merge(prev_class, pages_per_zspage, objs_per_zspage)) { pool->size_class[i] = prev_class; continue ; } } class = kzalloc( sizeof ( struct size_class), GFP_KERNEL); if (! class ) goto err; class ->size = size; class ->index = i; class ->pages_per_zspage = pages_per_zspage; class ->objs_per_zspage = objs_per_zspage; spin_lock_init(& class ->lock); pool->size_class[i] = class ; for (fullness = ZS_EMPTY; fullness < NR_ZS_FULLNESS; fullness++) INIT_LIST_HEAD(& class ->fullness_list[fullness]); prev_class = class ; } /* debug only, don't abort if it fails */ zs_pool_stat_create(pool, name); if (zs_register_migration(pool)) goto err; /* * Not critical since shrinker is only used to trigger internal * defragmentation of the pool which is pretty optional thing. If * registration fails we still can use the pool normally and user can * trigger compaction manually. Thus, ignore return code. */ zs_register_shrinker(pool); return pool; err: zs_destroy_pool(pool); return NULL; } |