linux-kernel - Re: [PATCH kernfs 1/3] kernfs: switch global kernfs_idr

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Message-ID: <2025041256-sanction-sandal-7f51@gregkh>
Date: Sat, 12 Apr 2025 08:12:22 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: alexjlzheng@...il.com
Cc: tj@...nel.org, alexjlzheng@...cent.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH kernfs 1/3] kernfs: switch global kernfs_idr_lock to
 per-fs lock

On Sat, Apr 12, 2025 at 02:31:07AM +0800, alexjlzheng@...il.com wrote:
> From: Jinliang Zheng <alexjlzheng@...cent.com>
> 
> The kernfs implementation has big lock granularity(kernfs_idr_lock) so
> every kernfs-based(e.g., sysfs, cgroup) fs are able to compete the lock.
> 
> This patch switches the global kernfs_idr_lock to per-fs lock, which
> put the spinlock into kernfs_root.
> 
> Signed-off-by: Jinliang Zheng <alexjlzheng@...cent.com>
> ---
>  fs/kernfs/dir.c             | 14 +++++++-------
>  fs/kernfs/kernfs-internal.h |  1 +
>  2 files changed, 8 insertions(+), 7 deletions(-)

What kind of testing / benchmark did you do for this series that shows
that this works, AND that this actually is measureable?  What workload
are you doing that causes these changes to be needed?

thanks,

greg k-h