linux-kernel - Re: [LKP] [lkp] [xfs] 68a9f5e700: aim7.jobs-per-min -13.6% regression

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Date:	Thu, 11 Aug 2016 20:20:53 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Christoph Hellwig <hch@....de>
Cc:	Dave Chinner <david@...morbit.com>,
	"Huang, Ying" <ying.huang@...el.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Bob Peterson <rpeterso@...hat.com>,
	Wu Fengguang <fengguang.wu@...el.com>, LKP <lkp@...org>
Subject: Re: [LKP] [lkp] [xfs] 68a9f5e700: aim7.jobs-per-min -13.6% regression

On Thu, Aug 11, 2016 at 7:52 PM, Christoph Hellwig <hch@....de> wrote:
>
> I can look at that, but indeed optimizing this patch seems a bit
> stupid.

The "write less than a full block to the end of the file" is actually
a reasonably common case.

It may not make for a great filesystem benchmark, but it also isn't
actually insane. People who do logging in user space do this all the
time, for example. And it is *not* stupid in that context. Not at all.

It's never going to be the *main* thing you do (unless you're AIM),
but I do think it's worth fixing.

And AIM7 remains one of those odd benchmarks that people use. I'm not
quite sure why, but I really do think that the normal "append smaller
chunks to the end of the file" should absolutely not be dismissed as
stupid.

                Linus