From: Javier Gonzalez <javier@cnexlabs.com>
To: Randy Dunlap <rdunlap@infradead.org>
CC: =?utf-8?B?TWF0aWFzIEJqw7hybGluZw==?= <m@bjorling.me>,
        Jens Axboe <axboe@fb.com>,
        "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "Hans Holmberg (C)" <hans.holmberg@cnexlabs.com>
Subject: Re: [GIT PULL 18/25] lightnvm: set target over-provision on create
 ioctl
Thread-Topic: [GIT PULL 18/25] lightnvm: set target over-provision on create
 ioctl
Thread-Index: AQHThid5Ni7fXf6Z1ESl/E9DppO7pqNlq+mAgAAFJwA=
Date: Fri, 5 Jan 2018 19:52:19 +0000
Message-ID: <D8E890A0-DBC8-4C0C-9AB9-62D9BB1CC9F2@cnexlabs.com>
References: <20180105131621.20808-1-m@bjorling.me>
 <20180105131621.20808-19-m@bjorling.me>
 <fd47bd97-8ff7-1f6a-b07f-c86449ec1834@infradead.org>
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> On 5 Jan 2018, at 20.33, Randy Dunlap <rdunlap@infradead.org> wrote:
>=20
> On 01/05/2018 05:16 AM, Matias Bj=C3=B8rling wrote:
>> From: Javier Gonz=C3=A1lez <javier@cnexlabs.com>
>>=20
>> Allow to set the over-provision percentage on target creation. In =
case
>> that the value is not provided, fall back to the default value set by
>> the target.
>>=20
>> In pblk, set the default OP to 11% of the total size of the device
>=20
>> +#define PBLK_DEFAULT_OP (11)
>=20
> Hi,
> Just curious -- where does 11 come from?  Is it a spec value?

11 stands for 11% over-provisioning for the media to allow garbage
collection. Different SSDs have different values based on the targeted
workload - 11% is a common default value for standard drives.

The spec. does not specify any default values of over-provisioning.

Javier.

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