Date: Mon, 15 Oct 2018 17:37:02 +0300 From: Yuri Pankov <yuripv@yuripv.net> To: Daniel Nebdal <dnebdal@gmail.com>, Current <freebsd-current@freebsd.org> Subject: Re: vm_fault on boot with NVMe/nda Message-ID: <1bb0a463-7630-e182-edb6-d02a868704d8@yuripv.net> In-Reply-To: <CA%2Bt49PKUVP9MYyx05KkGcF_=qpsPm_yajHN15Ak-uPuhtcZsmw@mail.gmail.com> References: <CA%2Bt49PKUVP9MYyx05KkGcF_=qpsPm_yajHN15Ak-uPuhtcZsmw@mail.gmail.com>
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From: Yuri Pankov <yuripv@yuripv.net>
To: Daniel Nebdal <dnebdal@gmail.com>, Current <freebsd-current@freebsd.org>
Message-ID: <1bb0a463-7630-e182-edb6-d02a868704d8@yuripv.net>
Subject: Re: vm_fault on boot with NVMe/nda
References: <CA+t49PKUVP9MYyx05KkGcF_=qpsPm_yajHN15Ak-uPuhtcZsmw@mail.gmail.com>
In-Reply-To: <CA+t49PKUVP9MYyx05KkGcF_=qpsPm_yajHN15Ak-uPuhtcZsmw@mail.gmail.com>
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Daniel Nebdal wrote:
> Hi. I have a 12-ALPHA9 / r339331 amd64 system (a HPE ProLiant ML30 G9),=
> with a Kingston NVMe SSD ("KINGSTON SKC1000480G") on a PCIe card.
>=20
> By default, it shows up as /dev/nvd0, and this is how I installed the
> system. It has a single large UFS2 (with SJ and TRIM support) partition=
> mounted as /. (There's also a few other partitions on it that should be=
> irrelevant for this.) This works, but it does sometimes slow down for
> minutes at the time with disturbing queue lengths in gstat; on the orde=
r of
> tens of thousands. As I understand it, this is due to how TRIM operatio=
ns
> take precedence over everything else when using nvd ?
>=20
> Looking around, I noticed the nda driver for NVMe-through-CAM. To test =
it,
> I added hw.nvme.use_nvd=3D0 to loader.conf. On one level, this works: T=
he
> drive shows up as /dev/nda0 . On the other hand, trying to mount nda0p2=
as
> / floods the console with "vm_fault: pager read error, pid 1 (init)", a=
nd
> never finishes booting.
>=20
> What is more interesting is that if I boot from the drive, but mount an=
> alpha9 usb stick as /, I can then mount the nda device just fine, and t=
he
> very minimal testing I did (using bin/cat and COPYRIGHT on the NVMe dri=
ve)
> seems to work.
>=20
> So - is nda meant to be bootable, or am I a bit over-eager in trying to=
do
> so?
> If not, is there anything smart I can do to get better performance out =
of
> nvd?
> (Or have I just overlooked something obvious?)
>=20
> Dmesg from a normal nvd boot here:
> https://openbenchmarking.org/system/1810159-RA-SSD30089593/SSD/dmesg
FWIW, I set hw.nvme.use_nvd=3D0 in the installer, got 12-ALPHA8 installed=
on nda0, and it's happily booting from it (using ZFS, though), so it's
certainly meant to be bootable.
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