linux-kernel - Re: [linus:master] [xfs] 2edf06a50f: fsmark.files_per

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Message-ID: <20230509065433.GT3223426@dread.disaster.area>
Date:   Tue, 9 May 2023 16:54:33 +1000
From:   Dave Chinner <david@...morbit.com>
To:     kernel test robot <oliver.sang@...el.com>
Cc:     Dave Chinner <dchinner@...hat.com>, oe-lkp@...ts.linux.dev,
        lkp@...el.com, linux-kernel@...r.kernel.org,
        "Darrick J. Wong" <djwong@...nel.org>, linux-xfs@...r.kernel.org,
        ying.huang@...el.com, feng.tang@...el.com, fengwei.yin@...el.com
Subject: Re: [linus:master] [xfs]  2edf06a50f:  fsmark.files_per_sec -5.7%
 regression

On Tue, May 09, 2023 at 10:13:19AM +0800, kernel test robot wrote:
> 
> 
> Hello,
> 
> kernel test robot noticed a -5.7% regression of fsmark.files_per_sec on:
> 
> 
> commit: 2edf06a50f5bbe664283f3c55c480fc013221d70 ("xfs: factor xfs_alloc_vextent_this_ag() for  _iterate_ags()")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master

This is just a refactoring patch and doesn't change any logic.
Hence I'm sceptical that it actually resulted in a performance
regression. Indeed, the profile indicates a significant change of
behaviour in the allocator and I can't see how the commit above
would cause anything like that.

Was this a result of a bisect? If so, what were the original kernel
versions where the regression was detected?

Cheers,

Dave.

-- 
Dave Chinner
david@...morbit.com