Date: Wed, 10 Dec 2014 12:33:50 +0000
From: Joe Thornber <thornber@redhat.com>
To: Akira Hayakawa <ruby.wktk@gmail.com>
Cc: ejt@redhat.com, dm-devel@redhat.com, gregkh@linuxfoundation.org,
        snitzer@redhat.com, agk@redhat.com, linux-kernel@vger.kernel.org
Subject: Re: [dm-devel] [PATCH] staging: writeboost: Add dm-writeboost
Message-ID: <20141210123349.GC21108@debian>
Mail-Followup-To: Akira Hayakawa <ruby.wktk@gmail.com>, ejt@redhat.com,
	dm-devel@redhat.com, gregkh@linuxfoundation.org, snitzer@redhat.com,
	agk@redhat.com, linux-kernel@vger.kernel.org
References: <5484498E.4000202@gmail.com>
 <20141207200834.GA2322@kroah.com>
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 <20141209151253.GA17660@debian>
 <20141210100033.GA21108@debian>
 <548827BD.3050803@gmail.com>
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On Wed, Dec 10, 2014 at 08:00:13PM +0900, Akira Hayakawa wrote:
> Hi, Joe
> 
> Thanks for continuous evaluation.

Some more details:

dd, with block size 512b
------------------------

raw spindle      : 143
writeboost Type 0: 137
writeboost Type 1: 130

dd, with block size 4k
----------------------

raw spindle      : 31
writeboost Type 0: 29
writeboost Type 1: 81


dd, with block size 64m
-----------------------

raw spindle      : 8.9
writeboost Type 0: 32
writeboost Type 1: 72


So maybe it's just volume of IO that's causing the problem?  What's
the difference between Type 0 and Type 1?  In the code I notice you
have 'rambuf' structures, are you caching IO in memory?

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