Commit 3c092fdb authored by Jinshan Xiong's avatar Jinshan Xiong Committed by Greg Kroah-Hartman
Browse files

staging: lustre: clio: revise read ahead algorithm 



ras_window_len should only be updated in ras_update() by read
pattern and it can't be adjusted in ll_readahead() at all;
ras_consecutive_pages is used to detect read pattern from
mmap. It will be used to increase read ahead window length
gradually.

Signed-off-by: default avatarJinshan Xiong <jinshan.xiong@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5505
Reviewed-on: http://review.whamcloud.com/11528


Reviewed-by: default avatarJohn L. Hammond <john.hammond@intel.com>
Reviewed-by: default avatarBobi Jam <bobijam@hotmail.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 86558182

drivers/staging/lustre/lustre/llite/llite_internal.h

+4 −1
Original line number Diff line number Diff line
@@ -1005,8 +1005,11 @@ const struct xattr_handler *get_xattr_type(const char *name); 
 */

int cl_sb_init(struct super_block *sb);

int cl_sb_fini(struct super_block *sb);

void ll_io_init(struct cl_io *io, const struct file *file, int write);



enum ras_update_flags {

	LL_RAS_HIT  = 0x1,

	LL_RAS_MMAP = 0x2

};

void ll_ra_count_put(struct ll_sb_info *sbi, unsigned long len);

void ll_ra_stats_inc(struct inode *inode, enum ra_stat which);

drivers/staging/lustre/lustre/llite/rw.c

+39 −32
Original line number Diff line number Diff line
@@ -457,17 +457,7 @@ static int ll_readahead(const struct lu_env *env, struct cl_io *io, 


	spin_lock(&ras->ras_lock);



	/* Enlarge the RA window to encompass the full read */

	if (vio->vui_ra_valid &&

	    ras->ras_window_start + ras->ras_window_len <

	    vio->vui_ra_start + vio->vui_ra_count) {

		ras->ras_window_len = vio->vui_ra_start + vio->vui_ra_count -

				      ras->ras_window_start;

	}



	/* Reserve a part of the read-ahead window that we'll be issuing */

	if (ras->ras_window_len > 0) {

		/*

	/**

	 * Note: other thread might rollback the ras_next_readahead,

	 * if it can not get the full size of prepared pages, see the

	 * end of this function. For stride read ahead, it needs to
@@ -475,12 +465,17 @@ static int ll_readahead(const struct lu_env *env, struct cl_io *io, 
	 * so that stride read ahead can work correctly.

	 */

	if (stride_io_mode(ras))

			start = max(ras->ras_next_readahead,

				    ras->ras_stride_offset);

		start = max(ras->ras_next_readahead, ras->ras_stride_offset);

	else

		start = ras->ras_next_readahead;



	if (ras->ras_window_len > 0)

		end = ras->ras_window_start + ras->ras_window_len - 1;

	}



	/* Enlarge the RA window to encompass the full read */

	if (vio->vui_ra_valid &&

	    end < vio->vui_ra_start + vio->vui_ra_count - 1)

		end = vio->vui_ra_start + vio->vui_ra_count - 1;



	if (end != 0) {

		unsigned long rpc_boundary;
@@ -602,7 +597,7 @@ static void ras_reset(struct inode *inode, struct ll_readahead_state *ras, 
	ras->ras_consecutive_pages = 0;

	ras->ras_window_len = 0;

	ras_set_start(inode, ras, index);

	ras->ras_next_readahead = max(ras->ras_window_start, index);

	ras->ras_next_readahead = max(ras->ras_window_start, index + 1);



	RAS_CDEBUG(ras);

}
@@ -733,10 +728,11 @@ static void ras_increase_window(struct inode *inode, 


static void ras_update(struct ll_sb_info *sbi, struct inode *inode,

		       struct ll_readahead_state *ras, unsigned long index,

		       unsigned int hit)

		       enum ras_update_flags flags)

{

	struct ll_ra_info *ra = &sbi->ll_ra_info;

	int zero = 0, stride_detect = 0, ra_miss = 0;

	bool hit = flags & LL_RAS_HIT;



	spin_lock(&ras->ras_lock);
@@ -766,7 +762,7 @@ static void ras_update(struct ll_sb_info *sbi, struct inode *inode, 
	 * to for subsequent IO.  The mmap case does not increment

	 * ras_requests and thus can never trigger this behavior.

	 */

	if (ras->ras_requests == 2 && !ras->ras_request_index) {

	if (ras->ras_requests >= 2 && !ras->ras_request_index) {

		__u64 kms_pages;



		kms_pages = (i_size_read(inode) + PAGE_SIZE - 1) >>
@@ -778,8 +774,7 @@ static void ras_update(struct ll_sb_info *sbi, struct inode *inode, 
		if (kms_pages &&

		    kms_pages <= ra->ra_max_read_ahead_whole_pages) {

			ras->ras_window_start = 0;

			ras->ras_last_readpage = 0;

			ras->ras_next_readahead = 0;

			ras->ras_next_readahead = index + 1;

			ras->ras_window_len = min(ra->ra_max_pages_per_file,

				ra->ra_max_read_ahead_whole_pages);

			goto out_unlock;
@@ -867,8 +862,13 @@ static void ras_update(struct ll_sb_info *sbi, struct inode *inode, 
	/* Trigger RA in the mmap case where ras_consecutive_requests

	 * is not incremented and thus can't be used to trigger RA

	 */

	if (!ras->ras_window_len && ras->ras_consecutive_pages == 4) {

		ras->ras_window_len = RAS_INCREASE_STEP(inode);

	if (ras->ras_consecutive_pages >= 4 && flags & LL_RAS_MMAP) {

		ras_increase_window(inode, ras, ra);

		/*

		 * reset consecutive pages so that the readahead window can

		 * grow gradually.

		 */

		ras->ras_consecutive_pages = 0;

		goto out_unlock;

	}
@@ -1101,9 +1101,16 @@ static int ll_io_read_page(const struct lu_env *env, struct cl_io *io, 


	vpg = cl2vvp_page(cl_object_page_slice(page->cp_obj, page));

	if (sbi->ll_ra_info.ra_max_pages_per_file > 0 &&

	    sbi->ll_ra_info.ra_max_pages > 0)

		ras_update(sbi, inode, ras, vvp_index(vpg),

			   vpg->vpg_defer_uptodate);

	    sbi->ll_ra_info.ra_max_pages > 0) {

		struct vvp_io *vio = vvp_env_io(env);

		enum ras_update_flags flags = 0;



		if (vpg->vpg_defer_uptodate)

			flags |= LL_RAS_HIT;

		if (!vio->vui_ra_valid)

			flags |= LL_RAS_MMAP;

		ras_update(sbi, inode, ras, vvp_index(vpg), flags);

	}



	if (vpg->vpg_defer_uptodate) {

		vpg->vpg_ra_used = 1;

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