Messages in this thread | | | Date | Tue, 4 Jan 2022 08:40:30 +0100 | From | Greg KH <> | Subject | Re: [RFC PATCH v2 1/2] kernfs: use kernfs_node specific mutex and spinlock. |
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On Tue, Jan 04, 2022 at 09:16:03AM +1100, Imran Khan wrote: > > There is a tradeoff of memory usage and runtime contention that has to > > be made here, and this might be pushing it in the wrong direction for > > a lot of systems. > > > Agree. Could you please suggest if this should be made configurable via > kconfig ? I understand that this would result in 2 versions of some > functions but it will allow systems with large memories to avoid kernfs > contention.
No, that way lies madness and horrible bugs and a codebase no one will be able to maintain.
> We are seeing the launch time of some DB workloads adversely getting > affected with this contention.
What workloads? sysfs should NEVER be in the fast-path of any normal operation, including booting. What benchmark or real-work is having problems here?
> Also based on recent movement of kernfs_rwsem into kernfs_root, do you > think that the above mentioned mutex and spinlock can be moved to > kernfs_root as well. Although that change would not help in my current > case, but it could avoid similar contentions between different users of > kernfs like cgroup and sysfs
Why would you want to move it if you do not see a measured benefit?
thanks,
greg k-h
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