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Date: Fri, 2 Dec 2016 19:53:15 -0500
From: James Simmons <jsimmons@...radead.org>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
devel@...verdev.osuosl.org,
Andreas Dilger <andreas.dilger@...el.com>,
Oleg Drokin <oleg.drokin@...el.com>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Lustre Development List <lustre-devel@...ts.lustre.org>,
Jinshan Xiong <jinshan.xiong@...el.com>,
James Simmons <jsimmons@...radead.org>
Subject: [PATCH 08/22] staging: lustre: clio: revise read ahead algorithm
From: Jinshan Xiong <jinshan.xiong@...el.com>
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@...el.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@...el.com>
Reviewed-by: Bobi Jam <bobijam@...mail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@...el.com>
Signed-off-by: James Simmons <jsimmons@...radead.org>
---
.../staging/lustre/lustre/llite/llite_internal.h | 5 +-
drivers/staging/lustre/lustre/llite/rw.c | 71 +++++++++++---------
2 files changed, 43 insertions(+), 33 deletions(-)
diff --git a/drivers/staging/lustre/lustre/llite/llite_internal.h b/drivers/staging/lustre/lustre/llite/llite_internal.h
index ae0bb09..e37ba1f 100644
--- a/drivers/staging/lustre/lustre/llite/llite_internal.h
+++ b/drivers/staging/lustre/lustre/llite/llite_internal.h
@@ -1005,8 +1005,11 @@ int ll_xattr_list(struct inode *inode, const char *name, int type,
*/
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);
diff --git a/drivers/staging/lustre/lustre/llite/rw.c b/drivers/staging/lustre/lustre/llite/rw.c
index e34017d..e2d5e75 100644
--- a/drivers/staging/lustre/lustre/llite/rw.c
+++ b/drivers/staging/lustre/lustre/llite/rw.c
@@ -457,30 +457,25 @@ 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;
- }
+ /**
+ * 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;
- /* 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;
+ 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;
--
1.7.1
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