On Wed, Feb 21, 2018, 15:13 Ernest Zed <kreuzerkrieg(a)gmail.com> wrote:
20us I mentioned it is by vendor (Intel) spec. I think preconditioning is
irrelevant for now, it only can degrade performance, not to improve.
Meanwhile, on not preconditioned drive I cant get spec latency.
Well, if you're after verifying the spec rather than assesing real latency
under unticipated workload, you should first inquire what the specified
latency refers to.
On Wed, Feb 21, 2018 at 1:50 PM, Andrey Kuzmin <andrey.v.kuzmin(a)gmail.com>
> On Wed, Feb 21, 2018, 12:55 Ernest Zed <kreuzerkrieg(a)gmail.com> wrote:
>> Hi all,
>> It is a follow-up question on getting maximum performance from NVMe (
). I have
>> unexplained latency numbers I get from `perf`, it hovering around 200us.
>> Which is quite high I think. Even when I drop to queue depth 1 I still get
>> 30us which is higher than the spec is claiming - 20us
> You might want to check with your SSD vendor what exactly the spec is
> referring to, but physical MLC page read is typically in excess of 100us
> (write latency differs thanks to onboard cache).
> Notice also that, unless you first precondition the drives properly,
> latency data will likely be irrelevant as drive's controller will know
> you're reading unwritten range and hence won't access the physical medium.
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