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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: Jinshan 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: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jinshan Xiong 2016-12-02 19:53:15 -05:00 committed by Greg Kroah-Hartman
parent 8655818239
commit 3c092fdbdb
2 changed files with 43 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
drivers/staging/lustre/lustre/llite/llite_internal.h
View File

@ -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);

71
drivers/staging/lustre/lustre/llite/rw.c
View File

@ -457,30 +457,25 @@ static int ll_readahead(const struct lu_env *env, struct cl_io *io,
spin_lock(&ras->ras_lock);
/**
* 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
* make sure the offset is no less than ras_stride_offset,
* so that stride read ahead can work correctly.
*/
if (stride_io_mode(ras))
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 &&
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
* make sure the offset is no less than ras_stride_offset,
* so that stride read ahead can work correctly.
*/
if (stride_io_mode(ras))
start = max(ras->ras_next_readahead,
ras->ras_stride_offset);
else
start = ras->ras_next_readahead;
end = ras->ras_window_start + ras->ras_window_len - 1;
}
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;