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Commit bc32a0de authored by Jinshan Xiong's avatar Jinshan Xiong Committed by Greg Kroah-Hartman
Browse files

staging: lustre: osc: add and fixup comments for LRU handling 



Add new information about the fields in struct client_obd.

Signed-off-by: default avatarJinshan Xiong <jinshan.xiong@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5108
Reviewed-on: http://review.whamcloud.com/10458


Reviewed-by: default avatarBobi Jam <bobijam@hotmail.com>
Reviewed-by: default avatarFan Yong <fan.yong@intel.com>
Reviewed-by: default avatarOleg Drokin <oleg.drokin@intel.com>
Signed-off-by: default avatarJames Simmons <jsimmons@infradead.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 884a1369

drivers/staging/lustre/lustre/include/obd.h

+23 −4
Original line number Original line Diff line number Diff line
@@ -247,15 +247,34 @@ struct client_obd { 
	struct obd_histogram     cl_read_offset_hist;

	struct obd_histogram     cl_read_offset_hist;

	struct obd_histogram     cl_write_offset_hist;

	struct obd_histogram     cl_write_offset_hist;





	/* lru for osc caching pages */

	/* LRU for osc caching pages */

	struct cl_client_cache	*cl_cache;

	struct cl_client_cache	*cl_cache;

	struct list_head	 cl_lru_osc; /* member of cl_cache->ccc_lru */

	/** member of cl_cache->ccc_lru */

	struct list_head	 cl_lru_osc;

	/** # of available LRU slots left in the per-OSC cache.

	 * Available LRU slots are shared by all OSCs of the same file system,

	 * therefore this is a pointer to cl_client_cache::ccc_lru_left.

	 */

	atomic_long_t		*cl_lru_left;

	atomic_long_t		*cl_lru_left;

	/** # of busy LRU pages. A page is considered busy if it's in writeback

	 * queue, or in transfer. Busy pages can't be discarded so they are not

	 * in LRU cache.

	 */

	atomic_long_t		 cl_lru_busy;

	atomic_long_t		 cl_lru_busy;

	/** # of LRU pages in the cache for this client_obd */

	atomic_long_t		 cl_lru_in_list;

	atomic_long_t		 cl_lru_in_list;

	/** # of threads are shrinking LRU cache. To avoid contention, it's not

	 * allowed to have multiple threads shrinking LRU cache.

	 */

	atomic_t		 cl_lru_shrinkers;

	atomic_t		 cl_lru_shrinkers;

	struct list_head	 cl_lru_list; /* lru page list */

	/** List of LRU pages for this client_obd */

	spinlock_t		 cl_lru_list_lock; /* page list protector */

	struct list_head	 cl_lru_list;

	/** Lock for LRU page list */

	spinlock_t		 cl_lru_list_lock;

	/** # of unstable pages in this client_obd.

	 * An unstable page is a page state that WRITE RPC has finished but

	 * the transaction has NOT yet committed.

	 */

	atomic_long_t		 cl_unstable_count;

	atomic_long_t		 cl_unstable_count;





	/* number of in flight destroy rpcs is limited to max_rpcs_in_flight */

	/* number of in flight destroy rpcs is limited to max_rpcs_in_flight */

drivers/staging/lustre/lustre/osc/osc_page.c

+12 −5
Original line number Original line Diff line number Diff line
@@ -343,16 +343,17 @@ void osc_page_submit(const struct lu_env *env, struct osc_page *opg, 
 * OSC to free slots voluntarily to maintain a reasonable number of free slots

 * OSC to free slots voluntarily to maintain a reasonable number of free slots

 * at any time.

 * at any time.

 */

 */



static DECLARE_WAIT_QUEUE_HEAD(osc_lru_waitq);

static DECLARE_WAIT_QUEUE_HEAD(osc_lru_waitq);

/* LRU pages are freed in batch mode. OSC should at least free this



 * number of pages to avoid running out of LRU budget, and..

/**

 * LRU pages are freed in batch mode. OSC should at least free this

 * number of pages to avoid running out of LRU slots.

 */

 */

static const int lru_shrink_min = 2 << (20 - PAGE_SHIFT);  /* 2M */

static const int lru_shrink_min = 2 << (20 - PAGE_SHIFT);  /* 2M */

/* free this number at most otherwise it will take too long time to finish. */

static const int lru_shrink_max = 8 << (20 - PAGE_SHIFT); /* 8M */

static const int lru_shrink_max = 8 << (20 - PAGE_SHIFT); /* 8M */





/* Check if we can free LRU slots from this OSC. If there exists LRU waiters,

/**

 * Check if we can free LRU slots from this OSC. If there exists LRU waiters,

 * we should free slots aggressively. In this way, slots are freed in a steady

 * we should free slots aggressively. In this way, slots are freed in a steady

 * step to maintain fairness among OSCs.

 * step to maintain fairness among OSCs.

 *

 *
@@ -643,6 +644,12 @@ long osc_lru_shrink(const struct lu_env *env, struct client_obd *cli, 
	return count > 0 ? count : rc;

	return count > 0 ? count : rc;

}

}





/**

 * Reclaim LRU pages by an IO thread. The caller wants to reclaim at least

 * \@npages of LRU slots. For performance consideration, it's better to drop

 * LRU pages in batch. Therefore, the actual number is adjusted at least

 * max_pages_per_rpc.

 */

long osc_lru_reclaim(struct client_obd *cli)

long osc_lru_reclaim(struct client_obd *cli)

{

{

	struct lu_env *env;

	struct lu_env *env;