Message-ID: <54E75B70.1010007@gmail.com>
Date: Sat, 21 Feb 2015 01:06:08 +0900
From: Akira Hayakawa <ruby.wktk@gmail.com>
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To: ejt@redhat.com
CC: Greg KH <gregkh@linuxfoundation.org>, snitzer@redhat.com,
        dm-devel@redhat.com, driverdev-devel@linuxdriverproject.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] staging: writeboost: Add dm-writeboost
References: <54A508F7.1020207@gmail.com> <20150118000952.GB26160@kroah.com> <20150220174401.4badb3cbad7be3eed449f4c1@gmail.com> <20150220150614.GA4740@debian> <54E75201.9030202@gmail.com> <20150220155036.GB4740@debian>
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The size is configurable but typically 512KB (that's the default).

Refer to bio payload sounds really dangerous but it may be possible
in some tricky way. but at the moment I am not sure how the
implementation would be.

Is there some fancy function that is like memcpy but actually "move"
the ownership?

- Akira

On 2015/02/21 0:50, Joe Thornber wrote:
> On Sat, Feb 21, 2015 at 12:25:53AM +0900, Akira Hayakawa wrote:
>> Yes.
> How big are your log chunks?  Presumably they're relatively small (eg,
> 256k).  In which case you can optimise for the common case where you
> have enough bios to hand to build your log chunk by just referencing
> the bio payloads, rather than copying.  It's only the last bit of io
> in a burst that should be using this copying slow path.
>
> - Joe

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