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Date:      Mon, 7 Mar 2016 16:48:28 +0100
From:      Borja Marcos <borjam@sarenet.es>
To:        Jim Harris <jim.harris@gmail.com>
Cc:        FreeBSD-STABLE Mailing List <freebsd-stable@freebsd.org>, John Baldwin <jhb@freebsd.org>
Subject:   Re: FreeBSD 10.3 - nvme regression
Message-ID:  <9499E409-3573-47A7-ABF9-043FC4870FEE@sarenet.es>
In-Reply-To: <CAJP=Hc8Oxz2bigh%2BbwgV1VRZuDWE%2BMHK5tJcpv-SD34sQfy%2BzQ@mail.gmail.com>
References:  <5A6B5C6F-26D1-40C5-8CCF-26EB8F17C59A@sarenet.es> <CAJP=Hc8Oxz2bigh%2BbwgV1VRZuDWE%2BMHK5tJcpv-SD34sQfy%2BzQ@mail.gmail.com>

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> On 07 Mar 2016, at 15:28, Jim Harris <jim.harris@gmail.com> wrote:
> (Moving to freebsd-stable.  NVMe is not associated with the SCSI stack =
at all.)

Oops, my apologies. I was assuming that, being storage stuff, -scsi was =
a good list.=20

> Can you please file a bug report on this?

Sure, doing doing some simple tests right now and I=E2=80=99ll file it.


>=20
> Also, can you try setting the following loader variable before =
install?
>=20
> hw.nvme.min_cpus_per_ioq=3D4

It now boots, thanks :)

Note that it=E2=80=99s the first time I use NVMe drives, so bear with me =
in case I do anything stupid ;)

I have noticed some odd performance problems. I have created a =
=E2=80=9Craidz2=E2=80=9D ZFS pool with the 10 drives.

Doing some silly tests with several =E2=80=9CBonnie++=E2=80=9D =
instances, I have noticed that delete commands seem to be
very slow. After running several bonnie++ instances in parallel, when =
deleting the files, the drivers
are almost stuck for a fairly long time, showing 100% bandwidth usage on =
=E2=80=9Cgstat=E2=80=9D and indeed being painfully
slow.

Disabling the usage of BIO_DELETE for ZFS (sysctl =
vfs.zfs.vdev.bio_delete_disable=3D1) solves this problem, although,
of course, BIO_DELETE is desirable as far as I know.=20

I observed the same behavior on 10.2.

This is not a proper report, I know, I will follow up tomorrow.=20

Thanks!





Borja.




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