On Fri, Mar 11, 2016 at 9:31 AM, Warner Losh wrote:
>
>
>
> And keep in mind the original description was this:
>
> Quote:
>
> Intel NVMe controllers have a slow path for I/Os that span
> a 128KB stripe boundary but ZFS limits ashift, which is derived
> from d_stripesize, to 13 (8KB) so we limit
On Fri, Mar 11, 2016 at 9:24 AM, Warner Losh wrote:
>
>
> On Fri, Mar 11, 2016 at 9:15 AM, Alan Somers wrote:
>
>> Interesting. I didn't know about the alternate meaning of stripesize. I
>> agree then that there's currently no way to tune ZFS to respect NVME's
>> 128KB boundaries. One could s
On Fri, Mar 11, 2016 at 9:15 AM, Alan Somers wrote:
> Interesting. I didn't know about the alternate meaning of stripesize. I
> agree then that there's currently no way to tune ZFS to respect NVME's
> 128KB boundaries. One could set zfs.vfs.vdev.aggregation_limit to 128KB,
> but that would onl
Interesting. I didn't know about the alternate meaning of stripesize. I
agree then that there's currently no way to tune ZFS to respect NVME's
128KB boundaries. One could set zfs.vfs.vdev.aggregation_limit to 128KB,
but that would only halfway solve the problem, because allocations could be
unal
On 11.03.16 06:58, Alan Somers wrote:
> Do they behave badly for writes that cross a 128KB boundary, but are
> nonetheless aligned to 128KB boundaries? Then I don't understand how
> this change (or mav's replacement) is supposed to help. The stripesize
> is supposed to be the minimum write that t
Do they behave badly for writes that cross a 128KB boundary, but are
nonetheless aligned to 128KB boundaries? Then I don't understand how this
change (or mav's replacement) is supposed to help. The stripesize is
supposed to be the minimum write that the device can accept without
requiring a read-
Some Intel NVMe drives behave badly when the LBA range crosses a 128k
boundary. Their
performance is worse for those transactions than for ones that don't cross
the 128k boundary.
Warner
On Thu, Mar 10, 2016 at 11:01 AM, Alan Somers wrote:
> Are you saying that Intel NVMe controllers perform po
Are you saying that Intel NVMe controllers perform poorly for all I/Os that
are less than 128KB, or just for I/Os of any size that cross a 128KB
boundary?
On Thu, Dec 10, 2015 at 7:06 PM, Steven Hartland wrote:
> Author: smh
> Date: Fri Dec 11 02:06:03 2015
> New Revision: 292074
> URL: https://
Author: smh
Date: Fri Dec 11 02:06:03 2015
New Revision: 292074
URL: https://svnweb.freebsd.org/changeset/base/292074
Log:
Limit stripesize reported from nvd(4) to 4K
Intel NVMe controllers have a slow path for I/Os that span a 128KB stripe
boundary but ZFS limits ashift, which is derived
