xnu-1228.tar.gz

[apple/xnu.git] / osfmk / vm / vm_purgeable_internal.h

diff --git a/osfmk/vm/vm_purgeable_internal.h b/osfmk/vm/vm_purgeable_internal.h
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+/*
+ * Copyright (c) 2007 Apple Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ * 
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ * 
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+/*
+ * Purgeable spelling rules
+ * It is believed that the correct spelling is 
+ * { 'p', 'u', 'r', 'g', 'e', 'a', 'b', 'l', 'e' }.
+ * However, there is one published API that likes to spell it without the
+ * first 'e', vm_purgable_control(). Since we can't change that API,
+ * here are the rules.
+ * All qualifiers defined in vm_purgable.h are spelled without the e.
+ * All other qualifiers are spelled with the e.
+ * Right now, there are remains of the wrong spelling throughout the code,
+ * vm_object_t.purgable for example. We expect to change these on occasion.
+ */
+
+#ifndef __VM_PURGEABLE_INTERNAL__
+#define __VM_PURGEABLE_INTERNAL__
+
+#include <kern/queue.h>
+
+enum purgeable_q_type {
+       PURGEABLE_Q_TYPE_OBSOLETE,
+       PURGEABLE_Q_TYPE_FIFO,
+       PURGEABLE_Q_TYPE_LIFO,
+       PURGEABLE_Q_TYPE_MAX
+};
+
+/* 
+ * It appears there's a 16 vs 32 size mismatch when using
+ * CONFIG_TOKEN_QUEUE_SMALL and the resulting math can lead to a large 
+ * negative value for new_pages in vm_purgeable.c.
+ */
+#if (CONFIG_TOKEN_QUEUE_SMALL == 1) && 0
+typedef uint16_t token_idx_t;
+typedef uint16_t token_cnt_t;
+#define MAX_VOLATILE 0x01000
+#define TOKEN_COUNT_MAX UINT16_MAX
+#else
+typedef uint32_t token_idx_t;
+typedef uint32_t token_cnt_t;
+#define MAX_VOLATILE 0x10000
+#define TOKEN_COUNT_MAX UINT32_MAX
+#endif
+
+#define NUM_VOLATILE_GROUPS 8
+struct purgeable_q {
+       token_idx_t token_q_head;    /* first token */
+       token_idx_t token_q_tail;    /* last token  */
+       token_idx_t token_q_unripe;  /* first token which is not ripe */
+       int32_t new_pages;
+       queue_head_t objq[NUM_VOLATILE_GROUPS];
+       enum purgeable_q_type type;
+#if MACH_ASSERT
+       int debug_count_tokens;
+       int debug_count_objects;
+#endif
+};
+
+typedef struct purgeable_q * purgeable_q_t;
+
+extern struct purgeable_q purgeable_queues[PURGEABLE_Q_TYPE_MAX];
+extern token_cnt_t token_new_pagecount;
+extern int available_for_purge;
+
+
+/*
+ * Locking:
+ * the token counters are protected by the vm_page_queue_lock, since they're
+ * mostly used in that context and we don't want to do a lot of extra locking
+ * the purgeable page queues are protected by a separate lock since they're
+ * mostly user on a user context and we don't want any contention with the
+ * pageout daemon.
+ */
+
+decl_mutex_data(,vm_purgeable_queue_lock)
+
+/* add a new token to queue. called by vm_object_purgeable_control */
+/* enter with page queue locked */
+kern_return_t vm_purgeable_token_add(purgeable_q_t queue);
+
+/* enter with page queue locked */
+void vm_purgeable_token_delete_first(purgeable_q_t queue);
+
+/*
+ * decrement token counters. the function will call the object purger if a
+ * token expires.
+ */
+/* enter with page queue locked */
+void vm_purgeable_q_advance_all(uint32_t num_pages);
+
+/* the object purger. purges the specified number of objects from memory. */
+void vm_purgeable_object_purge_one(void);
+
+/* insert purgeable object into queue */
+void vm_purgeable_object_add(vm_object_t object, purgeable_q_t queue, int group);
+
+/* Look for page belonging to object. If found, put on inactive queue. */
+purgeable_q_t vm_purgeable_object_remove(vm_object_t object);
+
+#endif /* __VM_PURGEABLE_INTERNAL__ */