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From: Al Viro <viro@zeniv.linux.org.uk>
To: kernel test robot <rong.a.chen@intel.com>
Cc: "zhengbin (A)" <zhengbin13@huawei.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	lkp@01.org, Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: c25aa432ff:  aim9.dir_rtns_1.ops_per_sec -24.5% regression
Date: Wed, 18 Sep 2019 02:23:00 +0100	[thread overview]
Message-ID: <20190918012300.GI1131@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20190918001736.GK15734@shao2-debian>

On Wed, Sep 18, 2019 at 08:17:36AM +0800, kernel test robot wrote:
> Greeting,
> 
> FYI, we noticed a -24.5% regression of aim9.dir_rtns_1.ops_per_sec due to commit:
> 
> 
> commit: c25aa432ff56e179bf5414edff3aa430d2b260c0 ("Fix the locking in dcache_readdir() and friends")
> https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next.git master

... and that, folks, is ->d_lock on the parent.  I.e. the original reason for
trying to do the damn thing lockless.

I'd really like to do a lockless variant, properly.  First we'd need to sort
the misuses of d_subdirs/d_child, though - there are several outright bugs
in the mainline.  And right now it looks like it wants to grow a series of
cleanups in autofs.  Oh, well...

      reply	other threads:[~2019-09-18  1:23 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-18  0:17 c25aa432ff: aim9.dir_rtns_1.ops_per_sec -24.5% regression kernel test robot
2019-09-18  1:23 ` Al Viro [this message]

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