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| author | Trond Myklebust <trond.myklebust@primarydata.com> | 2017-07-11 23:53:48 +0200 |
|---|---|---|
| committer | Anna Schumaker <Anna.Schumaker@Netapp.com> | 2017-07-13 22:57:18 +0200 |
| commit | 301bfa483016d48b7fb9cbad87c0a04a15c25b90 (patch) | |
| tree | 1e86b94a773529cae5a3144e03ff7b35f7673188 /fs | |
| parent | nfs: add export operations (diff) | |
| download | linux-301bfa483016d48b7fb9cbad87c0a04a15c25b90.tar.xz linux-301bfa483016d48b7fb9cbad87c0a04a15c25b90.zip | |
NFS: Don't run wake_up_bit() when nobody is waiting...
"perf lock" shows fairly heavy contention for the bit waitqueue locks
when doing an I/O heavy workload.
Use a bit to tell whether or not there has been contention for a lock
so that we can optimise away the bit waitqueue options in those cases.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/nfs/pagelist.c | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c index 8a23e2b40b04..de9066a92c0d 100644 --- a/fs/nfs/pagelist.c +++ b/fs/nfs/pagelist.c @@ -155,9 +155,12 @@ nfs_page_group_lock(struct nfs_page *req, bool nonblock) if (!test_and_set_bit(PG_HEADLOCK, &head->wb_flags)) return 0; - if (!nonblock) + if (!nonblock) { + set_bit(PG_CONTENDED1, &head->wb_flags); + smp_mb__after_atomic(); return wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK, TASK_UNINTERRUPTIBLE); + } return -EAGAIN; } @@ -175,6 +178,10 @@ nfs_page_group_lock_wait(struct nfs_page *req) WARN_ON_ONCE(head != head->wb_head); + if (!test_bit(PG_HEADLOCK, &head->wb_flags)) + return; + set_bit(PG_CONTENDED1, &head->wb_flags); + smp_mb__after_atomic(); wait_on_bit(&head->wb_flags, PG_HEADLOCK, TASK_UNINTERRUPTIBLE); } @@ -193,6 +200,8 @@ nfs_page_group_unlock(struct nfs_page *req) smp_mb__before_atomic(); clear_bit(PG_HEADLOCK, &head->wb_flags); smp_mb__after_atomic(); + if (!test_bit(PG_CONTENDED1, &head->wb_flags)) + return; wake_up_bit(&head->wb_flags, PG_HEADLOCK); } @@ -383,6 +392,8 @@ void nfs_unlock_request(struct nfs_page *req) smp_mb__before_atomic(); clear_bit(PG_BUSY, &req->wb_flags); smp_mb__after_atomic(); + if (!test_bit(PG_CONTENDED2, &req->wb_flags)) + return; wake_up_bit(&req->wb_flags, PG_BUSY); } @@ -465,6 +476,10 @@ void nfs_release_request(struct nfs_page *req) int nfs_wait_on_request(struct nfs_page *req) { + if (!test_bit(PG_BUSY, &req->wb_flags)) + return 0; + set_bit(PG_CONTENDED2, &req->wb_flags); + smp_mb__after_atomic(); return wait_on_bit_io(&req->wb_flags, PG_BUSY, TASK_UNINTERRUPTIBLE); } |