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| author | Imran Khan <imran.f.khan@oracle.com> | 2022-06-15 12:10:59 +1000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-06-27 16:46:15 +0200 |
| commit | 1d25b84e444ad66313c473407979ea9cd33deb3f (patch) | |
| tree | 604303c8fd0e7e70045eb87e4a4f3dc7d0705b35 /fs/kernfs/file.c | |
| parent | 41448c614815965d1cdfa720df34257b84afbb9d (diff) | |
| download | linux-1d25b84e444ad66313c473407979ea9cd33deb3f.tar.gz | |
kernfs: Replace global kernfs_open_file_mutex with hashed mutexes.
In current kernfs design a single mutex, kernfs_open_file_mutex, protects the list of kernfs_open_file instances corresponding to a sysfs attribute. So even if different tasks are opening or closing different sysfs files they can contend on osq_lock of this mutex. The contention is more apparent in large scale systems with few hundred CPUs where most of the CPUs have running tasks that are opening, accessing or closing sysfs files at any point of time. Using hashed mutexes in place of a single global mutex, can significantly reduce contention around global mutex and hence can provide better scalability. Moreover as these hashed mutexes are not part of kernfs_node objects we will not see any singnificant change in memory utilization of kernfs based file systems like sysfs, cgroupfs etc. Modify interface introduced in previous patch to make use of hashed mutexes. Use kernfs_node address as hashing key. Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Imran Khan <imran.f.khan@oracle.com> Link: https://lore.kernel.org/r/20220615021059.862643-5-imran.f.khan@oracle.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/kernfs/file.c')
| -rw-r--r-- | fs/kernfs/file.c | 17 |
1 files changed, 3 insertions, 14 deletions
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c index 3b354caad6b5..bb933221b4ba 100644 --- a/fs/kernfs/file.c +++ b/fs/kernfs/file.c @@ -18,19 +18,6 @@ #include "kernfs-internal.h" -/* - * There's one kernfs_open_file for each open file and one kernfs_open_node - * for each kernfs_node with one or more open files. - * - * kernfs_node->attr.open points to kernfs_open_node. attr.open is - * RCU protected. - * - * filp->private_data points to seq_file whose ->private points to - * kernfs_open_file. kernfs_open_files are chained at - * kernfs_open_node->files, which is protected by kernfs_open_file_mutex. - */ -static DEFINE_MUTEX(kernfs_open_file_mutex); - struct kernfs_open_node { struct rcu_head rcu_head; atomic_t event; @@ -51,7 +38,9 @@ static LLIST_HEAD(kernfs_notify_list); static inline struct mutex *kernfs_open_file_mutex_ptr(struct kernfs_node *kn) { - return &kernfs_open_file_mutex; + int idx = hash_ptr(kn, NR_KERNFS_LOCK_BITS); + + return &kernfs_locks->open_file_mutex[idx]; } static inline struct mutex *kernfs_open_file_mutex_lock(struct kernfs_node *kn) |