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NFS: Use cond_resched_lock() to reduce latencies in the commit scans

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Ensure that we conditionally drop the inode->i_lock when it is safe
to do so in the commit loops.
We do so after locking the nfs_page, but before removing it from the
commit list. We can then use list_safe_reset_next to recover the loop
after the lock is retaken.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust 2012-03-17 11:59:30 -04:00
parent 5ae67c4fee
commit 3b3be88d67
3 changed files with 20 additions and 10 deletions
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11
fs/nfs/nfs4filelayout.c
View file

@ -936,7 +936,8 @@ static struct pnfs_layout_segment *find_only_write_lseg(struct inode *inode)
} }
static int static int
filelayout_scan_ds_commit_list(struct nfs4_fl_commit_bucket *bucket, int max) filelayout_scan_ds_commit_list(struct nfs4_fl_commit_bucket *bucket, int max,
spinlock_t *lock)
{ {
struct list_head *src = &bucket->written; struct list_head *src = &bucket->written;
struct list_head *dst = &bucket->committing; struct list_head *dst = &bucket->committing;
@ -946,6 +947,8 @@ filelayout_scan_ds_commit_list(struct nfs4_fl_commit_bucket *bucket, int max)
list_for_each_entry_safe(req, tmp, src, wb_list) { list_for_each_entry_safe(req, tmp, src, wb_list) {
if (!nfs_lock_request(req)) if (!nfs_lock_request(req))
continue; continue;
if (cond_resched_lock(lock))
list_safe_reset_next(req, tmp, wb_list);
nfs_request_remove_commit_list(req); nfs_request_remove_commit_list(req);
clear_bit(PG_COMMIT_TO_DS, &req->wb_flags); clear_bit(PG_COMMIT_TO_DS, &req->wb_flags);
nfs_list_add_request(req, dst); nfs_list_add_request(req, dst);
@ -959,7 +962,8 @@ filelayout_scan_ds_commit_list(struct nfs4_fl_commit_bucket *bucket, int max)
/* Move reqs from written to committing lists, returning count of number moved. /* Move reqs from written to committing lists, returning count of number moved.
* Note called with i_lock held. * Note called with i_lock held.
*/ */
static int filelayout_scan_commit_lists(struct inode *inode, int max) static int filelayout_scan_commit_lists(struct inode *inode, int max,
spinlock_t *lock)
{ {
struct pnfs_layout_segment *lseg; struct pnfs_layout_segment *lseg;
struct nfs4_filelayout_segment *fl; struct nfs4_filelayout_segment *fl;
@ -972,7 +976,8 @@ static int filelayout_scan_commit_lists(struct inode *inode, int max)
if (fl->commit_through_mds) if (fl->commit_through_mds)
goto out_done; goto out_done;
for (i = 0; i < fl->number_of_buckets && max != 0; i++) { for (i = 0; i < fl->number_of_buckets && max != 0; i++) {
cnt = filelayout_scan_ds_commit_list(&fl->commit_buckets[i], max); cnt = filelayout_scan_ds_commit_list(&fl->commit_buckets[i],
max, lock);
max -= cnt; max -= cnt;
rv += cnt; rv += cnt;
} }

8
fs/nfs/pnfs.h
View file

@ -97,7 +97,7 @@ struct pnfs_layoutdriver_type {
void (*mark_request_commit) (struct nfs_page *req, void (*mark_request_commit) (struct nfs_page *req,
struct pnfs_layout_segment *lseg); struct pnfs_layout_segment *lseg);
void (*clear_request_commit) (struct nfs_page *req); void (*clear_request_commit) (struct nfs_page *req);
int (*scan_commit_lists) (struct inode *inode, int max); int (*scan_commit_lists) (struct inode *inode, int max, spinlock_t *lock);
int (*commit_pagelist)(struct inode *inode, struct list_head *mds_pages, int how); int (*commit_pagelist)(struct inode *inode, struct list_head *mds_pages, int how);
/* /*
@ -294,14 +294,14 @@ pnfs_clear_request_commit(struct nfs_page *req)
} }
static inline int static inline int
pnfs_scan_commit_lists(struct inode *inode, int max) pnfs_scan_commit_lists(struct inode *inode, int max, spinlock_t *lock)
{ {
struct pnfs_layoutdriver_type *ld = NFS_SERVER(inode)->pnfs_curr_ld; struct pnfs_layoutdriver_type *ld = NFS_SERVER(inode)->pnfs_curr_ld;
int ret; int ret;
if (ld == NULL || ld->scan_commit_lists == NULL) if (ld == NULL || ld->scan_commit_lists == NULL)
return 0; return 0;
ret = ld->scan_commit_lists(inode, max); ret = ld->scan_commit_lists(inode, max, lock);
if (ret != 0) if (ret != 0)
set_bit(NFS_INO_PNFS_COMMIT, &NFS_I(inode)->flags); set_bit(NFS_INO_PNFS_COMMIT, &NFS_I(inode)->flags);
return ret; return ret;
@ -419,7 +419,7 @@ pnfs_clear_request_commit(struct nfs_page *req)
} }
static inline int static inline int
pnfs_scan_commit_lists(struct inode *inode, int max) pnfs_scan_commit_lists(struct inode *inode, int max, spinlock_t *lock)
{ {
return 0; return 0;
} }

11
fs/nfs/write.c
View file

@ -561,7 +561,8 @@ nfs_need_commit(struct nfs_inode *nfsi)
/* i_lock held by caller */ /* i_lock held by caller */
static int static int
nfs_scan_commit_list(struct list_head *src, struct list_head *dst, int max) nfs_scan_commit_list(struct list_head *src, struct list_head *dst, int max,
spinlock_t *lock)
{ {
struct nfs_page *req, *tmp; struct nfs_page *req, *tmp;
int ret = 0; int ret = 0;
@ -569,6 +570,8 @@ nfs_scan_commit_list(struct list_head *src, struct list_head *dst, int max)
list_for_each_entry_safe(req, tmp, src, wb_list) { list_for_each_entry_safe(req, tmp, src, wb_list) {
if (!nfs_lock_request(req)) if (!nfs_lock_request(req))
continue; continue;
if (cond_resched_lock(lock))
list_safe_reset_next(req, tmp, wb_list);
nfs_request_remove_commit_list(req); nfs_request_remove_commit_list(req);
nfs_list_add_request(req, dst); nfs_list_add_request(req, dst);
ret++; ret++;
@ -596,8 +599,10 @@ nfs_scan_commit(struct inode *inode, struct list_head *dst)
if (nfsi->ncommit > 0) { if (nfsi->ncommit > 0) {
const int max = INT_MAX; const int max = INT_MAX;
ret = nfs_scan_commit_list(&nfsi->commit_list, dst, max); ret = nfs_scan_commit_list(&nfsi->commit_list, dst, max,
ret += pnfs_scan_commit_lists(inode, max - ret); &inode->i_lock);
ret += pnfs_scan_commit_lists(inode, max - ret,
&inode->i_lock);
} }
spin_unlock(&inode->i_lock); spin_unlock(&inode->i_lock);
return ret; return ret;