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Date: Fri, 1 Dec 2023 04:09:51 +0000
From: Al Viro <viro@zeniv.linux.org.uk>
To: Oliver Sang <oliver.sang@intel.com>
Cc: oe-lkp@lists.linux.dev, lkp@intel.com, linux-fsdevel@vger.kernel.org,
	Christian Brauner <brauner@kernel.org>, linux-doc@vger.kernel.org,
	ying.huang@intel.com, feng.tang@intel.com, fengwei.yin@intel.com
Subject: Re: [viro-vfs:work.dcache2] [__dentry_kill()]  1b738f196e:
 stress-ng.sysinfo.ops_per_sec -27.2% regression
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On Fri, Dec 01, 2023 at 10:13:09AM +0800, Oliver Sang wrote:

> > Very interesting...  Out of curiosity, what effect would the following
> > have on top of 1b738f196e?
> 
> I applied the patch upon 1b738f196e (as below fec356fd0c), but seems less
> useful.

I would be rather surprised if it fixed anything; it's just that 1b738f196e
changes two things - locking rules for __dentry_kill() and, in some cases,
the order of dentry eviction in shrink_dentry_list().  That delta on top of
it restores the original order in shrink_dentry_list(), leaving pretty much
the changes in lock_for_kill()/dput()/__dentry_kill().

Interesting...  Looks like there are serious changes in context switch
frequencies, but I don't see where could that have come from...