From 3b3be88d67cc17d0f0ab6edaf131516793fc947e Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Sat, 17 Mar 2012 11:59:30 -0400 Subject: [PATCH] NFS: Use cond_resched_lock() to reduce latencies in the commit scans 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 --- fs/nfs/nfs4filelayout.c | 11 ++++++++--- fs/nfs/pnfs.h | 8 ++++---- fs/nfs/write.c | 11 ++++++++--- 3 files changed, 20 insertions(+), 10 deletions(-) diff --git a/fs/nfs/nfs4filelayout.c b/fs/nfs/nfs4filelayout.c index e0bdbf4..634c0bc 100644 --- a/fs/nfs/nfs4filelayout.c +++ b/fs/nfs/nfs4filelayout.c @@ -936,7 +936,8 @@ static struct pnfs_layout_segment *find_only_write_lseg(struct inode *inode) } 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 *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) { if (!nfs_lock_request(req)) continue; + if (cond_resched_lock(lock)) + list_safe_reset_next(req, tmp, wb_list); nfs_request_remove_commit_list(req); clear_bit(PG_COMMIT_TO_DS, &req->wb_flags); 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. * 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 nfs4_filelayout_segment *fl; @@ -972,7 +976,8 @@ static int filelayout_scan_commit_lists(struct inode *inode, int max) if (fl->commit_through_mds) goto out_done; 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; rv += cnt; } diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h index e98ff30..0780265 100644 --- a/fs/nfs/pnfs.h +++ b/fs/nfs/pnfs.h @@ -97,7 +97,7 @@ struct pnfs_layoutdriver_type { void (*mark_request_commit) (struct nfs_page *req, struct pnfs_layout_segment *lseg); 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); /* @@ -294,14 +294,14 @@ pnfs_clear_request_commit(struct nfs_page *req) } 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; int ret; if (ld == NULL || ld->scan_commit_lists == NULL) return 0; - ret = ld->scan_commit_lists(inode, max); + ret = ld->scan_commit_lists(inode, max, lock); if (ret != 0) set_bit(NFS_INO_PNFS_COMMIT, &NFS_I(inode)->flags); return ret; @@ -419,7 +419,7 @@ pnfs_clear_request_commit(struct nfs_page *req) } 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; } diff --git a/fs/nfs/write.c b/fs/nfs/write.c index 628d9a6..bd93d40 100644 --- a/fs/nfs/write.c +++ b/fs/nfs/write.c @@ -561,7 +561,8 @@ nfs_need_commit(struct nfs_inode *nfsi) /* i_lock held by caller */ 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; 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) { if (!nfs_lock_request(req)) continue; + if (cond_resched_lock(lock)) + list_safe_reset_next(req, tmp, wb_list); nfs_request_remove_commit_list(req); nfs_list_add_request(req, dst); ret++; @@ -596,8 +599,10 @@ nfs_scan_commit(struct inode *inode, struct list_head *dst) if (nfsi->ncommit > 0) { const int max = INT_MAX; - ret = nfs_scan_commit_list(&nfsi->commit_list, dst, max); - ret += pnfs_scan_commit_lists(inode, max - ret); + ret = nfs_scan_commit_list(&nfsi->commit_list, dst, max, + &inode->i_lock); + ret += pnfs_scan_commit_lists(inode, max - ret, + &inode->i_lock); } spin_unlock(&inode->i_lock); return ret; -- 2.7.4