> On 5 Jan 2018, at 20.53, Matias Bjørling <m@xxxxxxxxxxx> wrote: > > On 01/05/2018 08:52 PM, Javier Gonzalez wrote: >>> On 5 Jan 2018, at 20.33, Randy Dunlap <rdunlap@xxxxxxxxxxxxx> wrote: >>> >>> On 01/05/2018 05:16 AM, Matias Bjørling wrote: >>>> From: Javier González <javier@xxxxxxxxxxxx> >>>> >>>> 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. >>>> >>>> In pblk, set the default OP to 11% of the total size of the device >>> >>>> +#define PBLK_DEFAULT_OP (11) >>> >>> 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. > > I think what Randy means is, why is the value not 20% or 7%, which is the traditional over-provisioning on SSDs. We decided 11% based on customer input, but 7% and 20% are also good default values. I'm ok with having any of those as default - anyone caring about OP will define the value on target creation, which is the primary objective of this patch. Javier
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