|
nfs-ganesha 1.4
|
Constant-time cache inode cache management implementation. More...
Go to the source code of this file.
Classes | |
| struct | lru_state |
Defines | |
| #define | LRU_N_Q_LANES 7 |
Functions | |
| void | cache_inode_lru_pkginit (void) |
| void | cache_inode_lru_pkgshutdown (void) |
| struct cache_entry_t * | cache_inode_lru_get (cache_inode_status_t *status, uint32_t flags) |
| Re-use or allocate an entry. | |
| cache_inode_status_t | cache_inode_lru_ref (cache_entry_t *entry, uint32_t flags) __attribute__((warn_unused_result)) |
| Get a reference. | |
| void | cache_inode_lru_kill (cache_entry_t *entry) |
| Destroy the sentinel refcount safely. | |
| void | cache_inode_lru_unref (cache_entry_t *entry, uint32_t flags) |
| Relinquish a reference. | |
| void | lru_wake_thread (uint32_t flags) |
| Wake the LRU thread to free FDs. | |
| cache_inode_status_t | cache_inode_inc_pin_ref (cache_entry_t *entry) |
| Function to let the state layer pin an entry. | |
| void | cache_inode_unpinnable (cache_entry_t *entry) |
| Make it impossible to pin an entry. | |
| cache_inode_status_t | cache_inode_dec_pin_ref (cache_entry_t *entry) |
| Function to let the state layer rlease a pin. | |
Variables | |
| struct lru_state | lru_state |
| size_t | open_fd_count |
Constant-time cache inode cache management implementation.
This module implements a constant-time cache management strategy based on LRU. Some ideas are taken from 2Q [Johnson and Shasha 1994] and MQ [Zhou, Chen, Li 2004]. In this system, cache management does interact with cache entry lifecycle. Also, the cache size high- and low- water mark management is maintained, but executes asynchronously to avoid inline request delay. Cache management operations execute in constant time, as expected with LRU (and MQ).
Cache entries in use by a currently-active protocol request (or other operation) have a positive refcount, and threfore should not be present at the cold end of an lru queue if the cache is well-sized.
Cache entries with lock and open state are not eligible for collection under ordinary circumstances, so are kept on a separate lru_pinned list to retain constant time.
Definition in file cache_inode_lru.h.
| #define LRU_N_Q_LANES 7 |
Definition at line 155 of file cache_inode_lru.h.
| cache_inode_status_t cache_inode_dec_pin_ref | ( | cache_entry_t * | entry | ) |
Function to let the state layer rlease a pin.
This function moves the given entry out of the pinned queue fragment for its lane. If the entry is not pinned, it is a no-op.
| [in] | entry | The entry to be moved |
| CACHE_INODE_SUCCESS | if the entry was moved. |
Definition at line 1211 of file cache_inode_lru.c.
| cache_inode_status_t cache_inode_inc_pin_ref | ( | cache_entry_t * | entry | ) |
Function to let the state layer pin an entry.
This function moves the given entry to the pinned queue fragment for its lane. If the entry is already pinned, it is a no-op.
| [in] | entry | The entry to be moved |
| CACHE_INODE_SUCCESS | if the entry was moved. |
| CACHE_INODE_DEAD_ENTRY | if the entry is in the process of disposal |
Definition at line 1155 of file cache_inode_lru.c.
| struct cache_entry_t* cache_inode_lru_get | ( | cache_inode_status_t * | status, |
| uint32_t | flags | ||
| ) | [read] |
Re-use or allocate an entry.
This function repurposes a resident entry in the LRU system if the system is above low-water mark, and allocates a new one otherwise. On success, this function always returns an entry with two references (one for the sentinel, one to allow the caller's use.)
| [in] | status | Returned status |
| [in] | flags | Flags governing call |
Definition at line 1056 of file cache_inode_lru.c.
| void cache_inode_lru_kill | ( | cache_entry_t * | entry | ) |
Destroy the sentinel refcount safely.
This function decrements the refcount by one unless the LRU_FLAG_KILLED bit is set in the flags word. This is intended to allow a function that needs to remove an extra refcount (the sentinel) to be called multiple times without causing an underflow.
| [in] | entry | The entry to decrement. |
Definition at line 1307 of file cache_inode_lru.c.
| void cache_inode_lru_pkginit | ( | void | ) |
Initialize subsystem
Definition at line 876 of file cache_inode_lru.c.
| void cache_inode_lru_pkgshutdown | ( | void | ) |
Shutdown subsystem
Definition at line 1032 of file cache_inode_lru.c.
| cache_inode_status_t cache_inode_lru_ref | ( | cache_entry_t * | entry, |
| uint32_t | flags | ||
| ) |
Get a reference.
This function acquires a reference on the given cache entry, if the entry is still live. Terrible things will happen if you call this function and don't check its return value.
| [in] | entry | The entry on which to get a reference |
| [in] | flags | Flags indicating the type of reference sought |
| CACHE_INODE_SUCCESS | if the reference was acquired |
| CACHE_INODE_DEAD_ENTRY | if the object is being disposed |
Definition at line 1247 of file cache_inode_lru.c.
| void cache_inode_lru_unref | ( | cache_entry_t * | entry, |
| uint32_t | flags | ||
| ) |
Relinquish a reference.
This function relinquishes a reference on the given cache entry. It follows the disposal/recycling lock discipline given at the beginning of the file.
The supplied entry is always either unlocked or destroyed by the time this function returns.
| [in] | entry | The entry on which to release a reference |
| [in] | flags | Currently significant are and LRU_FLAG_LOCKED (indicating that the caller holds the LRU mutex lock for this entry.) |
Definition at line 1337 of file cache_inode_lru.c.
| void cache_inode_unpinnable | ( | cache_entry_t * | entry | ) |
Make it impossible to pin an entry.
This function makes it impossible to pin an entry, but does not unpin it.
| [in] | entry | The entry to be moved |
Definition at line 1191 of file cache_inode_lru.c.
| void lru_wake_thread | ( | uint32_t | flags | ) |
Wake the LRU thread to free FDs.
This function wakes the LRU reaper thread to free FDs and should be called when we are over the high water mark.
| [in] | flags | Flags to affect the wake (currently none) |
Definition at line 1397 of file cache_inode_lru.c.
Definition at line 124 of file cache_inode_lru.c.
| size_t open_fd_count |
This is a global counter of files opened by cache_inode. This is preliminary expected to go away. Problems with this method are that it overcounts file descriptors for FSALs that don't use them for open files, and, under the Lieb Rearchitecture, FSALs will be responsible for caching their own file descriptors, with interfaces for Cache_Inode to interrogate them as to usage or instruct them to close them.
Definition at line 178 of file cache_inode_lru.c.
1.7.3