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Date: Fri, 12 Aug 2016 00:08:54 +0200
From: Christoph Hellwig <hch@lst.de>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Huang, Ying" <ying.huang@intel.com>, Christoph Hellwig <hch@lst.de>,
        Dave Chinner <david@fromorbit.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Bob Peterson <rpeterso@redhat.com>,
        Wu Fengguang <fengguang.wu@intel.com>, LKP <lkp@01.org>
Subject: Re: [LKP] [lkp] [xfs] 68a9f5e700: aim7.jobs-per-min -13.6%
	regression
Message-ID: <20160811220854.GA30146@lst.de>
References: <CA+55aFyQ6cjKOQZKEuQV9ch+aerW1Q6uGdv+pCS81rX0yjyR6w@mail.gmail.com> <8760r816wf.fsf@yhuang-mobile.sh.intel.com> <CA+55aFy=xeEKgfHWisfxsZNqrgMJxvKvhrWrPmdpMxu0pnOXig@mail.gmail.com> <20160811155721.GA23015@lst.de> <CA+55aFyVqdk0p6pmEx_gOs_AiH0TJ23ZEUDZHc9kiFbqEk8UOw@mail.gmail.com> <874m6ryz0u.fsf@yhuang-mobile.sh.intel.com> <CA+55aFzdnCDcf8nVtMTX7XiEoZVUqFahVA7kdns5aGKBWFqn3Q@mail.gmail.com> <20160811200018.GA28271@lst.de> <87ziojxazw.fsf@yhuang-mobile.sh.intel.com> <CA+55aFx=mbAd0hEnji-TWZH_NReLLk+SbJHK1s+=r1_USV0KXw@mail.gmail.com>
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I'll need to dig into what AIM7 actually does in this benchmark, which
isn't too easy as I'm on a business trip currently, but from the list
below it looks like it keeps overwriting and overwriting a file that's
already been allocated.  This is a pretty stupid workload, but fortunately
it should also be able to be optimized by skipping the actual block
lookup, which is what the old buffer.c code happens to do.

From mboxrd@z Thu Jan  1 00:00:00 1970
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From: Christoph Hellwig <hch@lst.de>
To: lkp@lists.01.org
Subject: Re: [xfs] 68a9f5e700: aim7.jobs-per-min -13.6% regression
Date: Fri, 12 Aug 2016 00:08:54 +0200
Message-ID: <20160811220854.GA30146@lst.de>
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I'll need to dig into what AIM7 actually does in this benchmark, which
isn't too easy as I'm on a business trip currently, but from the list
below it looks like it keeps overwriting and overwriting a file that's
already been allocated.  This is a pretty stupid workload, but fortunately
it should also be able to be optimized by skipping the actual block
lookup, which is what the old buffer.c code happens to do.

--===============3979296714299365003==--