From 03be85eb11f756414aafedca22f93a3351b727b8 Mon Sep 17 00:00:00 2001 From: Samuel Thibault Date: Thu, 27 Dec 2012 00:00:57 +0100 Subject: Optimise dir-lookup's second-lock This should avoid some lock contention. * libdiskfs/dir-lookup.c (diskfs_S_dir_lookup): Before releasing &np->lock to get &dnp->lock safely, try to lock &dnp->lock directly. * libtreefs/dir-lookup.c (_treefs_s_dir_lookup): Likewise. --- libdiskfs/dir-lookup.c | 9 ++++++--- libtreefs/dir-lookup.c | 9 ++++++--- 2 files changed, 12 insertions(+), 6 deletions(-) diff --git a/libdiskfs/dir-lookup.c b/libdiskfs/dir-lookup.c index 1efdf75c..923be033 100644 --- a/libdiskfs/dir-lookup.c +++ b/libdiskfs/dir-lookup.c @@ -310,9 +310,12 @@ diskfs_S_dir_lookup (struct protid *dircred, pthread_mutex_lock (&dnp->lock); else { - pthread_mutex_unlock (&np->lock); - pthread_mutex_lock (&dnp->lock); - pthread_mutex_lock (&np->lock); + if (pthread_mutex_trylock (&dnp->lock)) + { + pthread_mutex_unlock (&np->lock); + pthread_mutex_lock (&dnp->lock); + pthread_mutex_lock (&np->lock); + } } } } diff --git a/libtreefs/dir-lookup.c b/libtreefs/dir-lookup.c index ce2acafd..8665059c 100644 --- a/libtreefs/dir-lookup.c +++ b/libtreefs/dir-lookup.c @@ -199,9 +199,12 @@ _treefs_s_dir_lookup (struct treefs_handle *h, in the right order. */ if (strcmp (path, "..") != 0) { - pthread_mutex_unlock (&node->lock); - pthread_mutex_lock (&dir->lock); - pthread_mutex_lock (&node->lock); + if (pthread_mutex_trylock (&dir->lock)) + { + pthread_mutex_unlock (&node->lock); + pthread_mutex_lock (&dir->lock); + pthread_mutex_lock (&node->lock); + } } else pthread_mutex_lock (&dir->lock); -- cgit v1.2.3