Stability of 11.1S

Tue Mar 20 18:10:51 UTC 2018

(Please keep me CC'd as I am not subscribed to -stable)

I haven't seen any issues, but that means very little.  Details:

Two boxes -- one bare metal, one VPS (QEMU):

$ uname -a
FreeBSD XXXXXXXXXXXXXXX 11.1-STABLE FreeBSD 11.1-STABLE #0 r330529: Tue Mar  6 11:36:04 PST 2018     root at XXXXXXXXXXXXXXX:/usr/obj/usr/src/sys/X7SBA_RELENG_11_amd64  amd64
$ uptime
10:33a.m.  up 13 days, 18:10, 2 users, load averages: 0.15, 0.19, 0.16

$ uname -a
FreeBSD XXXXXXXXXXXXXXXX 11.1-STABLE FreeBSD 11.1-STABLE #0 r330753: Sat Mar 10 21:34:20 PST 2018     root at XXXXXXXXXXXXXXXX:/usr/obj/usr/src/sys/XXXXXXXX_RELENG_11_amd64  amd64
$ uptime
10:33a.m.  up 9 days, 10:46, 1 user, load averages: 0.31, 0.35, 0.31

Systems were updated recently because I wanted to test Meltdown/Spectre
mitigation (more on that below).  Prior to that, bare metal was running
9.x with 200+ day uptimes, VPS was running 10.x with 80-90 day uptimes
(VPS providers' HV crashed, i.e. not FreeBSD issues).

Since load averages on FreeBSD 10.x onward cannot be trusted[1][2], I
have to explain the general system specs and loads:

Bare metal box is an Intel Core 2 Quad Q9550, 8GB RAM, doing very little
other than running Apache + lots of cron jobs for systems stuff + ZFS
with several disks (but not OS disk; that's a dedicated SSD w/ UFS + SU
(not SUJ).  The cron jobs tend to stress the network and disk I/O a bit;
ZFS gets used every day, but only "heavily" during LAN file copies
to/from it (Samba is involved), and during nightly backups with rsync.

VPS box is some form of QEMU-based Intel Haswell CPU, 1GB RAM, doing
general things like Apache + postfix + SpamAssassin + some other
daemons, and a lot of Perl.  Swap is used heavily on this machine.
Disks are all vtblk, and I use multiple to get capacity for the needed
space for /usr/src and /usr/obj.  Everything is UFS + SU (not SUJ).

Things off the top of my head that might be relevant to you:

1. r329462 added Meltdown/Spectre mitigation[3][4].

Bare metal box has the below in /boot/loader.conf, since this is a
machine that does not need either given its environment:

# Disable PTI (Meltdown mitigation) and IBRS (Spectre mitigation); these
# are not relevant on this bare-metal system given its environment and
# use case.  Details of these tunables is here:
# https://lists.freebsd.org/pipermail/freebsd-stable/2018-March/088526.html
#
vm.pmap.pti="0"
hw.ibrs_disable="1"

VPS box has no tunings of this sort, and ends up with the below, because
the hosting provider has no done BIOS + QEMU updates to add IBRS
support (they're very aware of it + have attempted it twice but
apparently it didn't go well):

vm.pmap.pti: 1
hw.ibrs_disable: 1
hw.ibrs_active: 0

2. If your CPU is an AMD Ryzen, there is a VERY long discussion on
-stable about problems with Ryzen manifesting itself in a very
uncomfortable way, leading to system lock-ups[5].  There are unofficial
patches you can try.  I would recommend chiming in there and not here,
if relevant to your systems.

And yes, the massive number of MFCs that eadler@ is doing make tracking
down exact things more tedious than normal, especially when you have
sweeping commits like this one[6][7] (which, AFAIK, was acting as a
major blocker for several other MFCs and causing general merge
problems).

However, I commend his efforts; it's a massive undertaking (I would say
full-time job).  We stable users must accept that we are running
stable/11 for a reason -- not only to get fixes faster, but to act a
form of "guinea pig" that don't want the risks of HEAD/CURRENT.  The
more people using stable/11 the better overall feedback devs can get on
bugs/issues before making it into the next -RELEASE.  This is exactly
why, for those of you who have known me over the years, I actually
"track" or "follow" commits as they come across.  I do this by using the
FreshBSD site[8] alongside manual review of svnlite update output.  I
generally know what files/bits are relevant to my interests.

Hope this gives you some things to think about.  Good luck!

[1]: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=173541#c8
[2]: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=173541#c22
[3]: https://lists.freebsd.org/pipermail/freebsd-stable/2018-February/088396.html
[4]: https://lists.freebsd.org/pipermail/freebsd-stable/2018-March/088526.html
[5]: https://lists.freebsd.org/pipermail/freebsd-stable/2018-January/thread.html#88174
[6]: http://www.freshbsd.org/commit/freebsd/r330897
[7]: https://svnweb.freebsd.org/base?view=revision&revision=330897
[8]: http://www.freshbsd.org/?branch=RELENG_11&project=freebsd

-- 
| Jeremy Chadwick                                   jdc at koitsu.org |
| UNIX Systems Administrator                http://jdc.koitsu.org/ |
| Making life hard for others since 1977.             PGP 4BD6C0CB |