From mboxrd@z Thu Jan 1 00:00:00 1970 From: Akira Hayakawa Subject: Re: [PATCH v3] staging: writeboost: Add dm-writeboost Date: Sat, 21 Feb 2015 01:06:08 +0900 Message-ID: <54E75B70.1010007@gmail.com> References: <54A508F7.1020207@gmail.com> <20150118000952.GB26160@kroah.com> <20150220174401.4badb3cbad7be3eed449f4c1@gmail.com> <20150220150614.GA4740@debian> <54E75201.9030202@gmail.com> <20150220155036.GB4740@debian> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150220155036.GB4740@debian> Sender: linux-kernel-owner@vger.kernel.org To: ejt@redhat.com Cc: Greg KH , snitzer@redhat.com, dm-devel@redhat.com, driverdev-devel@linuxdriverproject.org, linux-kernel@vger.kernel.org List-Id: dm-devel.ids 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