From mboxrd@z Thu Jan  1 00:00:00 1970
Content-Type: multipart/mixed; boundary="===============0366101106078270871=="
MIME-Version: 1.0
From: Baruch Even <baruch at weka.io>
Subject: Re: [SPDK] Handling of physical disk removals
Date: Sun, 03 Jun 2018 11:35:39 +0300
Message-ID: <CAKye4Qbem2uiXkyOBNA7tBAp749=kuEQH5QSDNGOuxj_GNdH-g@mail.gmail.com>
In-Reply-To: A07631C3-3DBD-4F7F-B557-28CD62A5B6DB@intel.com
List-ID: <spdk@lists.01.org>
To: spdk@lists.01.org

--===============0366101106078270871==
Content-Type: text/plain; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: quoted-printable

On Fri, Jun 1, 2018 at 7:54 PM Harris, James R <james.r.harris(a)intel.com>
wrote:

>
> [=E2=80=A6]
>
>
>
> In regards to your concerns on I/O splitting - I think step one is making
> sure the driver has APIs to expose any device-specific characteristics su=
ch
> as sectors per stripe.  Step two is measuring the overhead of the splitti=
ng
> logic when splitting is not required.  Based on those measurements, we can
> consider optimizations and/or evaluate a bypass mode.  The bypass mode
> seems important to Weka.io =E2=80=93 would you like to submit an RFC for =
what this
> bypass mode might look like in more detail?
>
> What is needed for the RFC?
>
>
>
> It doesn=E2=80=99t need to be especially formal.  Basically, what your ne=
w API
> would look like and how it would impact the existing code at a reasonable
> level of detail.  Also, what tests you would plan to add to automate
> testing of the new API.  An RFC typically comes with an assumption that t=
he
> author plans to carry the work forward if and when a consensus has been
> reached.  If that assumption is not correct, it is best to clarify that up
> front.
>
>
>
> Any kind of empirical performance data is critical.  I=E2=80=99m really i=
nterested
> in seeing it.  The existing driver can get >4M IO/s on a single Xeon core,
> so the extra complexity and maintenance burden of the new API has to show
> demonstrable improvements.  Hopefully there would be no changes to the
> existing API, but if there are, that=E2=80=99s another data point that wo=
uld need
> to be considered.
>
>
>

That will take some time as it will require me to review the code and at
least flesh out a basic implementation to be able to show what changes are
needed and any performance impacts resulting. As I have other topics to
resolve at this time at work that are higher priority that will not be soon
enough but I take from it that there is an openness to consider such a
change.

Baruch
-- =




*Baruch Even, Software Developer  E  baruch(a)weka.io <liran(a)weka.io>
www.weka.io <http://www.weka.io>*

--===============0366101106078270871==
Content-Type: text/html
MIME-Version: 1.0
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="attachment.html"
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--===============0366101106078270871==--