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>
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