(Note: I hope this reply shows up correctly. I subscribed to the

mailing list after the fact and had to "forge" the subject line.)
Hey everyone,

I'm having serious trouble with the same thing, and just found this

thread while looking for the correct place to post. Looks like I found

it. (I wrote most of the post before finding the thread, so some of it

will seem a bit odd.)
I run 8.0-RC1/amd64 with ZFS on an A64 3200+ with 2GB RAM and an old

80GB 7200rpm disk.
My problem is that I get completely unacceptable latency on console IO

(both via SSH and serial console) when the system is performing disk

IO. The worst case I've noticed yet was when I tried copying a core

dump from a lzjb compressed ZFS file system to a gzip-9 compressed

one, to compare the file size/compression ratio. screen(1) took at

LEAST ten seconds - probably a bit more - I'm not exaggerating here -

to switch to another window, and an "ls" in an empty directory also

about 5-10 seconds.

Doing some silly CPU load with two instances of "yes >/dev/null" (on a

single core, remember) doesn't change anything, the system remains

very responsive. "cat /dev/zero > /uncompressed_fs/..." however

produces the extreme slowdown. (On a gzip-1 FS it doesn't, since the

file ends up extremely small - a kilobyte or so - even after a while,

thus performing minimal IO).
I'm thinking about switching to FreeBSD on my beefier "production"

system (dual-core amd64, 4GB RAM, 4x1TB disks, compared to this one,

single-core, 2GB RAM, 80GB disk), but unless I feel assured this won't

happen there as well, I'm not so sure anymore. I can do any kind of

heavy IO/compilation/whatever on that box, currently running Linux,

and it's always unnoticable. In this case it's impossible *not* to

notice that your key input is lagging behind 5-10 seconds... I thought

multiple times that the box must have panicked.

I do realize that the hardware isn't the best, especially the disks,

but this is far worse than it should be!
Here's some of the testing done in this thread (or at least something

like it):
[root@chaos ~]# time file /etc/* >/dev/null

real    0m1.725s

user    0m0.993s

sys     0m0.021s

[root@chaos ~]# time file /etc/* >/dev/null
real    0m1.008s

user    0m0.990s

sys     0m0.015s

[root@chaos ~]# time file /etc/* >/dev/null
real    0m1.008s

user    0m0.967s

sys     0m0.038s

[root@chaos ~]# time file /etc/* >/dev/null
real    0m1.015s

user    0m0.998s

sys     0m0.008s
So, pretty much exactly 1 second every time once the cache is warmed

up. Now, let's try it 10 seconds after starting heavy disk writing...
[root@chaos ~]# cat /dev/zero > /DELETE_ME &

(wait for 10 seconds)

[root@chaos ~]# time file /etc/* >/dev/null
real    0m13.217s

user    0m1.004s

sys     0m0.023s

[root@chaos ~]# time file /etc/* >/dev/null
real    0m24.012s

user    0m1.020s

sys     0m0.008s
... the numbers speak for themselves. FWIW I tried the same on the

Linux box: "file" took 0.8 seconds the first time, 0.125s subsequent

times. While running cat, 0.13-0.21 seconds (0.21 being the first,

subsequent runs took 0.13s). The system remained completely

responsive, which cannot be said for the FreeBSD one!
Any advice? Info below - please ask if you need more!
Regards,

Thomas
-----------------------------------------------------------------------------
Basic info:
[root@chaos ~]# uname -a

FreeBSD chaos.exscape.org 8.0-RC1 FreeBSD 8.0-RC1 #1 r197613M: Tue Sep

29 15:04:44 CEST 2009     root@chaos.exscape.org:/usr/obj/usr/src/sys/

DTRACE  amd64

(KDB/DDB enabled, WITNESS/INVARIANTS *disabled*)
[root@chaos ~]# mount

tank/root on / (zfs, local, noatime)

devfs on /dev (devfs, local, multilabel)

/dev/ad0s1a on /bootdir (ufs, local, soft-updates)

tank/export on /export (zfs, NFS exported, local, noatime)

tank/tmp on /tmp (zfs, local, noatime)

tank/usr on /usr (zfs, local, noatime)

tank/usr/obj on /usr/obj (zfs, local, noatime)

tank/usr/ports on /usr/ports (zfs, local, noatime)

tank/usr/ports/distfiles on /usr/ports/distfiles (zfs, local, noatime)

tank/usr/src on /usr/src (zfs, local, noatime)

tank/usr/src_r196905 on /usr/src_r196905 (zfs, local, noatime, read-

only)

tank/var on /var (zfs, local, noatime)

tank/var/crash on /var/crash (zfs, local, noatime)

tank/var/log on /var/log (zfs, local, noatime)

tank/var/tmp on /var/tmp (zfs, local, noatime)
dmesg:
-----------------------------------------------------------------------------

Copyright (c) 1992-2009 The FreeBSD Project.

Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994

	The Regents of the University of California. All rights reserved.

FreeBSD is a registered trademark of The FreeBSD Foundation.

FreeBSD 8.0-RC1 #1 r197613M: Tue Sep 29 15:04:44 CEST 2009

     root@chaos.exscape.org:/usr/obj/usr/src/sys/DTRACE

Timecounter "i8254" frequency 1193182 Hz quality 0

CPU: AMD Athlon(tm) 64 Processor 3200+ (2009.27-MHz K8-class CPU)

   Origin = "AuthenticAMD"  Id = 0x10ff0  Stepping = 0
Features

=

0x78bfbff

<

FPU

,VME

,DE

,PSE

,TSC

,MSR

,PAE

,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,MMX,FXSR,SSE,SSE2>

   AMD Features=0xe2500800

   AMD Features2=0x1

real memory  = 2147483648 (2048 MB)

avail memory = 2052362240 (1957 MB)

ACPI APIC Table:

ioapic0  irqs 0-23 on motherboard

kbd1 at kbdmux0

acpi0:  on motherboard

acpi0: [ITHREAD]

acpi0: Power Button (fixed)

acpi0: reservation of 0, a0000 (3) failed

acpi0: reservation of 100000, 7fef0000 (3) failed

Timecounter "ACPI-fast" frequency 3579545 Hz quality 1000

acpi_timer0: <24-bit timer at 3.579545MHz> port 0x4008-0x400b on acpi0

acpi_button0:  on acpi0

pcib0:  port 0xcf8-0xcff on acpi0

pci0:  on pcib0

pci0:  at device 0.0 (no driver attached)

isab0:  at device 1.0 on pci0

isa0:  on isab0

pci0:  at device 1.1 (no driver attached)

ohci0:  mem 0xfe02f000-0xfe02ffff irq

21 at device 2.0 on pci0

ohci0: [ITHREAD]

usbus0:  on ohci0

ehci0:  mem 0xfe02e000-0xfe02e0ff

irq 22 at device 2.1 on pci0

ehci0: [ITHREAD]

usbus1: EHCI version 1.0

usbus1:  on ehci0

atapci0:  port

0x1f0-0x1f7,0x3f6,0x170-0x177,0x376,0xfb00-0xfb0f at device 6.0 on pci0

ata0:  on atapci0

ata0: [ITHREAD]

ata1:  on atapci0

ata1: [ITHREAD]

atapci1:  port

0x9f0-0x9f7,0xbf0-0xbf3,0x970-0x977,0xb70-0xb73,0xf600-0xf60f mem

0xfe02b000-0xfe02bfff irq 23 at device 7.0 on pci0

atapci1: [ITHREAD]

ata2:  on atapci1

ata2: [ITHREAD]

ata3:  on atapci1

ata3: [ITHREAD]

atapci2:  port

0x9e0-0x9e7,0xbe0-0xbe3,0x960-0x967,0xb60-0xb63,0xf100-0xf10f mem

0xfe02a000-0xfe02afff irq 21 at device 8.0 on pci0

atapci2: [ITHREAD]

ata4:  on atapci2

ata4: [ITHREAD]

ata5:  on atapci2

ata5: [ITHREAD]

pcib1:  at device 9.0 on pci0

pci1:  on pcib1

vgapci0:  mem 0xfcff8000-0xfcffbfff,

0xfd000000-0xfd7fffff,0xfc000000-0xfc7fffff irq 17 at device 7.0 on pci1

xl0: <3Com 3c905C-TX Fast Etherlink XL> port 0xdf00-0xdf7f mem

0xfcfff000-0xfcfff07f irq 18 at device 9.0 on pci1

miibus0:  on xl0

xlphy0: <3c905C 10/100 internal PHY> PHY 24 on miibus0

xlphy0:  10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto

xl0: Ethernet address: 00:50:da:44:c0:4a

xl0: [ITHREAD]

nfe0:  port

0xf000-0xf007 mem 0xfe029000-0xfe029fff irq 22 at device 10.0 on pci0

miibus1:  on nfe0

e1000phy0:  PHY 1 on miibus1

e1000phy0:  10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, 1000baseT,

1000baseT-FDX, auto

nfe0: Ethernet address: 00:13:d3:a2:aa:0f

nfe0: [FILTER]

pcib2:  at device 11.0 on pci0

pci2:  on pcib2

pcib3:  at device 12.0 on pci0

pci3:  on pcib3

pcib4:  at device 13.0 on pci0

pci4:  on pcib4

pcib5:  at device 14.0 on pci0

pci5:  on pcib5

amdtemp0:  on hostb3

acpi_tz0:  on acpi0

atrtc0:  port 0x70-0x73 irq 8 on acpi0

uart0: <16550 or compatible> port 0x3f8-0x3ff irq 4 flags 0x10 on acpi0

uart0: [FILTER]

uart0: console (115200,n,8,1)

atkbdc0:  port 0x60,0x64 irq 1 on acpi0

atkbd0:  irq 1 on atkbdc0

kbd0 at atkbd0

atkbd0: [GIANT-LOCKED]

atkbd0: [ITHREAD]

cpu0:  on acpi0

powernow0:  on cpu0

device_attach: powernow0 attach returned 6

orm0:  at iomem 0xc0000-0xc7fff,0xc8000-0xcbfff,

0xcc000-0xcc7ff on isa0

sc0:  at flags 0x100 on isa0

sc0: VGA <16 virtual consoles, flags=0x300>

vga0:  at port 0x3c0-0x3df iomem 0xa0000-0xbffff on

isa0

ZFS NOTICE: system has less than 4GB and prefetch enable is not set...

disabling.

ZFS filesystem version 13

ZFS storage pool version 13

Timecounter "TSC" frequency 2009269513 Hz quality 800

Timecounters tick every 1.000 msec

usbus0: 12Mbps Full Speed USB v1.0

usbus1: 480Mbps High Speed USB v2.0

ad0: 76318MB  at ata0-master UDMA100

ugen0.1:  at usbus0

uhub0:  on

usbus0

ugen1.1:  at usbus1

uhub1:  on

usbus1

ad2: 9768MB  at ata1-master UDMA100

GEOM: ad2s1: geometry does not match label (255h,63s != 16h,63s).

Root mount waiting for: usbus1 usbus0

uhub0: 10 ports with 10 removable, self powered

Root mount waiting for: usbus1

Root mount waiting for: usbus1

Root mount waiting for: usbus1

uhub1: 10 ports with 10 removable, self powered

Trying to mount root from zfs:tank/root

netsmb_dev: loaded
-----------------------------------------------------------------------------

The 80GB disk is used for everything except swap (aka. dump device)

for which the 10GB disk is used, exclusively.
loader.conf has nothing of value (just loading a few modules and a

vfs.root.mountfrom, plus serial console settings).

_______________________________________________

freebsd-performance@freebsd.org mailing list

http://lists.freebsd.org/mailman/listinfo/freebsd-performance

To unsubscribe, send any mail to "freebsd-performance-unsubscribe@freebsd.org"