Date: Thu, 26 May 2022 03:37:48 +0000 From: John <jwd@freebsd.org> To: Adam Stylinski <kungfujesus06@gmail.com> Cc: freebsd-fs@freebsd.org, Rick Macklem <rmacklem@uoguelph.ca> Subject: Re: zfs/nfsd performance limiter Message-ID: <Yo72DLuJkm7lD%2B06@FreeBSD.org> In-Reply-To: <CAJwHY9W-3eEXR%2BjTw40thcio65Ukjw8qgnp-qPiS3bdeZS0kLw@mail.gmail.com> References: <CAJwHY9WMOOLy=rb9FNjExQtYej21Zv=Po9Cbg=19gkw1SLFSww@mail.gmail.com> <YonqGfJST09cUV6W@FreeBSD.org> <CAJwHY9W-3eEXR%2BjTw40thcio65Ukjw8qgnp-qPiS3bdeZS0kLw@mail.gmail.com>
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Hi Adam,
Sorry for the late reply to your original reply. Many good replies
from Rick cc'd (Hi Rick :-)
1 item pops out to me below.
----- Adam Stylinski's Original Message -----
> > What is your server system? Make/model/ram/etc.
> Intel(R) Xeon(R) CPU E5-2603 v4 @ 1.70GHz (6 cores, a little starved
> on the clock but the load at least is basically zero during this test)
> 128GB of memory
>
> > top -aH
> During the copy load (for brevity, only did the real top contenders for CPU here):
> last pid: 15560; load averages: 0.25, 0.39, 0.27 up 4+15:48:54 09:17:38
> 98 threads: 2 running, 96 sleeping
> CPU: 0.0% user, 0.0% nice, 19.1% system, 5.6% interrupt, 75.3% idle
> Mem: 12M Active, 4405M Inact, 8284K Laundry, 115G Wired, 1148M Buf, 4819M Free
> ARC: 98G Total, 80G MFU, 15G MRU, 772K Anon, 1235M Header, 1042M Other
> 91G Compressed, 189G Uncompressed, 2.09:1 Ratio
> Swap: 5120M Total, 5120M Free
>
> PID USERNAME PRI NICE SIZE RES STATE C TIME WCPU COMMAND
> 3830 root 20 0 12M 2700K rpcsvc 2 1:16 53.26% nfsd: server (nfsd){nfsd: service}
> 3830 root 20 0 12M 2700K CPU5 5 5:42 52.96% nfsd: server (nfsd){nfsd: master}
> 15560 adam 20 0 17M 5176K CPU2 2 0:00 0.12% top -aH
> 1493 root 20 0 13M 2260K select 3 0:36 0.01% /usr/sbin/powerd
> 1444 root 20 0 75M 2964K select 5 0:19 0.01% /usr/sbin/mountd -r /etc/exports /etc/zfs/exports
> 1215 uucp 20 0 13M 2820K select 5 0:27 0.01% /usr/local/libexec/nut/usbhid-ups -a cyberpower
> 93424 adam 20 0 21M 9900K select 0 0:00 0.01% sshd: adam@pts/0 (sshd)
>
> > ifconfig -vm
> mlxen0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 9000
> options=ed07bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4,TSO6,LRO,VLAN_HWFILTER,VLAN_HWTSO,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>
> capabilities=ed07bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4,TSO6,LRO,VLAN_HWFILTER,VLAN_HWTSO,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>
> ether 00:02:c9:35:df:20
> inet 10.5.5.1 netmask 0xffffff00 broadcast 10.5.5.255
> media: Ethernet autoselect (40Gbase-CR4 <full-duplex,rxpause,txpause>)
Something worth checking:
The media line indicates that rxpause/txpause are active for this
interface. I don't have a mlx based Linux system handy so the following
is from memory. On the Linux side, please try:
ethtool -S $interface | grep pause
The output should include the number of times a pause frame was
transmitted (Linux system NIC receive queue (almost) full) or a pause
frame was received (meaning the FreeBSD system NIC receive queue
(almost) full). If the values are 0 this is not an issue.
If rx/tx pause frames are being sent/received this will slow down
the link (rather dramatically sometimes). With only rx/tx pause (vs
dcbx) a system spewing pause frames can bring a set of connected
systems to a slow crawl.
-John
> status: active
> supported media:
> media autoselect
> media 40Gbase-CR4 mediaopt full-duplex
> media 10Gbase-CX4 mediaopt full-duplex
> media 10Gbase-SR mediaopt full-duplex
> media 1000baseT mediaopt full-duplex
> nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
> plugged: QSFP+ 40GBASE-CR4 (No separable connector)
> vendor: Mellanox PN: MC2207130-002 SN: MT1419VS07971 DATE: 2014-06-06
> module temperature: 0.00 C voltage: 0.00 Volts
> lane 1: RX power: 0.00 mW (-inf dBm) TX bias: 0.00 mA
> lane 2: RX power: 0.00 mW (-inf dBm) TX bias: 0.00 mA
> lane 3: RX power: 0.00 mW (-inf dBm) TX bias: 0.00 mA
> lane 4: RX power: 0.00 mW (-inf dBm) TX bias: 0.00 mA
>
> > - What are your values for:
> >
> > -- kern.ipc.maxsockbuf
> > -- net.inet.tcp.sendbuf_max
> > -- net.inet.tcp.recvbuf_max
> >
> > -- net.inet.tcp.sendspace
> > -- net.inet.tcp.recvspace
> >
> > -- net.inet.tcp.delayed_ack
> kern.ipc.maxsockbuf: 16777216
> net.inet.tcp.sendbuf_max: 16777216
> net.inet.tcp.recvbuf_max: 16777216
> net.inet.tcp.sendspace: 32768 # This is interesting? I'm not sure why
> the discrepancy here
> net.inet.tcp.recvspace: 4194304
> net.inet.tcp.delayed_ack: 0
>
> > netstat -i
> Name Mtu Network Address Ipkts Ierrs Idrop
> Opkts Oerrs Coll
> igb0 9000 <Link#1> ac:1f:6b:b0:60:bc 18230625 0 0
> 24178283 0 0
> igb1 9000 <Link#2> ac:1f:6b:b0:60:bc 14341213 0 0
> 8447249 0 0
> lo0 16384 <Link#3> lo0 367691 0 0
> 367691 0 0
> lo0 - localhost localhost 68 - -
> 68 - -
> lo0 - fe80::%lo0/64 fe80::1%lo0 0 - -
> 0 - -
> lo0 - your-net localhost 348944 - -
> 348944 - -
> mlxen 9000 <Link#4> 00:02:c9:35:df:20 13138046 0 12
> 26308206 0 0
> mlxen - 10.5.5.0/24 10.5.5.1 11592389 - -
> 24345184 - -
> vm-pu 9000 <Link#6> 56:3e:55:8a:2a:f8 7270 0 0
> 962249 102 0
> lagg0 9000 <Link#5> ac:1f:6b:b0:60:bc 31543941 0 0
> 31623674 0 0
> lagg0 - 192.168.0.0/2 nasbox 27967582 - -
> 41779731 - -
>
> > What threads/irq are allocated to your NIC? 'vmstat -i'
>
> Doesn't seem perfectly balanced but not terribly imbalanced, either:
>
> interrupt total rate
> irq9: acpi0 3 0
> irq18: ehci0 ehci1+ 803162 2
> cpu0:timer 67465114 167
> cpu1:timer 65068819 161
> cpu2:timer 65535300 163
> cpu3:timer 63408731 157
> cpu4:timer 63026304 156
> cpu5:timer 63431412 157
> irq56: nvme0:admin 18 0
> irq57: nvme0:io0 544999 1
> irq58: nvme0:io1 465816 1
> irq59: nvme0:io2 487486 1
> irq60: nvme0:io3 474616 1
> irq61: nvme0:io4 452527 1
> irq62: nvme0:io5 467807 1
> irq63: mps0 36110415 90
> irq64: mps1 112328723 279
> irq65: mps2 54845974 136
> irq66: mps3 50770215 126
> irq68: xhci0 3122136 8
> irq70: igb0:rxq0 1974562 5
> irq71: igb0:rxq1 3034190 8
> irq72: igb0:rxq2 28703842 71
> irq73: igb0:rxq3 1126533 3
> irq74: igb0:aq 7 0
> irq75: igb1:rxq0 1852321 5
> irq76: igb1:rxq1 2946722 7
> irq77: igb1:rxq2 9602613 24
> irq78: igb1:rxq3 4101258 10
> irq79: igb1:aq 8 0
> irq80: ahci1 37386191 93
> irq81: mlx4_core0 4748775 12
> irq82: mlx4_core0 13754442 34
> irq83: mlx4_core0 3551629 9
> irq84: mlx4_core0 2595850 6
> irq85: mlx4_core0 4947424 12
> Total 769135944 1908
>
> > Are the above threads floating or mapped? 'cpuset -g ...'
>
> I suspect I was supposed to run this against the argument of a pid,
> maybe nfsd? Here's the output without an argument
>
> pid -1 mask: 0, 1, 2, 3, 4, 5
> pid -1 domain policy: first-touch mask: 0
>
> > Disable nfs tcp drc
>
> This is the first I've even seen a duplicate request cache mentioned.
> It seems counter-intuitive for why that'd help but maybe I'll try
> doing that. What exactly is the benefit?
>
> > What is your atime setting?
>
> Disabled at both the file system and the client mounts.
>
> > You also state you are using a Linux client. Are you using the MLX affinity scripts, buffer sizing suggestions, etc, etc. Have you swapped the Linux system for a fbsd system?
> I've not, though I do vaguely recall mellanox supplying some scripts
> in their documentation that fixed interrupt handling on specific cores
> at one point. Is this what you're referring to? I could give that a
> try. I don't at present have any FreeBSD client systems with enough
> PCI express bandwidth to swap things out for a Linux vs FreeBSD test.
>
> > You mention iperf. Please post the options you used when invoking iperf and it's output.
>
> Setting up the NFS client as a "server", since it seems that the
> terminology is a little bit flipped with iperf, here's the output:
>
> -----------------------------------------------------------
> Server listening on 5201 (test #1)
> -----------------------------------------------------------
> Accepted connection from 10.5.5.1, port 11534
> [ 5] local 10.5.5.4 port 5201 connected to 10.5.5.1 port 43931
> [ ID] Interval Transfer Bitrate
> [ 5] 0.00-1.00 sec 3.81 GBytes 32.7 Gbits/sec
> [ 5] 1.00-2.00 sec 4.20 GBytes 36.1 Gbits/sec
> [ 5] 2.00-3.00 sec 4.18 GBytes 35.9 Gbits/sec
> [ 5] 3.00-4.00 sec 4.21 GBytes 36.1 Gbits/sec
> [ 5] 4.00-5.00 sec 4.20 GBytes 36.1 Gbits/sec
> [ 5] 5.00-6.00 sec 4.21 GBytes 36.2 Gbits/sec
> [ 5] 6.00-7.00 sec 4.10 GBytes 35.2 Gbits/sec
> [ 5] 7.00-8.00 sec 4.20 GBytes 36.1 Gbits/sec
> [ 5] 8.00-9.00 sec 4.21 GBytes 36.1 Gbits/sec
> [ 5] 9.00-10.00 sec 4.20 GBytes 36.1 Gbits/sec
> [ 5] 10.00-10.00 sec 7.76 MBytes 35.3 Gbits/sec
> - - - - - - - - - - - - - - - - - - - - - - - - -
> [ ID] Interval Transfer Bitrate
> [ 5] 0.00-10.00 sec 41.5 GBytes 35.7 Gbits/sec receiver
> -----------------------------------------------------------
> Server listening on 5201 (test #2)
> -----------------------------------------------------------
>
> On Sun, May 22, 2022 at 3:45 AM John <jwd@freebsd.org> wrote:
> >
> > ----- Adam Stylinski's Original Message -----
> > > Hello,
> > >
> > > I have two systems connected via ConnectX-3 mellanox cards in ethernet
> > > mode. They have their MTU's maxed at 9000, their ring buffers maxed
> > > at 8192, and I can hit around 36 gbps with iperf.
> > >
> > > When using an NFS client (client = linux, server = freebsd), I see a
> > > maximum rate of around 20gbps. The test file is fully in ARC. The
> > > test is performed with an NFS mount nconnect=4 and an rsize/wsize of
> > > 1MB.
> > >
> > > Here's the flame graph of the kernel of the system in question, with
> > > idle stacks removed:
> > >
> > > https://gist.github.com/KungFuJesus/918c6dcf40ae07767d5382deafab3a52#file-nfs_fg-svg
> > >
> > > The longest functions seems like maybe it's the ERMS aware memcpy
> > > happening from the ARC? Is there maybe a missing fast path that could
> > > take fewer copies into the socket buffer?
> >
> > Hi Adam -
> >
> > Some items to look at and possibly include for more responses....
> >
> > - What is your server system? Make/model/ram/etc. What is your
> > overall 'top' cpu utilization 'top -aH' ...
> >
> > - It looks like you're using a 40gb/s card. Posting the output of
> > 'ifconfig -vm' would provide additional information.
> >
> > - Are the interfaces running cleanly? 'netstat -i' is helpful.
> >
> > - Inspect 'netstat -s'. Duplicate pkts? Resends? Out-of-order?
> >
> > - Inspect 'netstat -m'. Denied? Delayed?
> >
> >
> > - You mention iperf. Please post the options you used when
> > invoking iperf and it's output.
> >
> > - You appear to be looking for through-put vs low-latency. Have
> > you looked at window-size vs the amount of memory allocated to the
> > streams. These values vary based on the bit-rate of the connection.
> > Tcp connections require outstanding un-ack'd data to be held.
> > Effects values below.
> >
> >
> > - What are your values for:
> >
> > -- kern.ipc.maxsockbuf
> > -- net.inet.tcp.sendbuf_max
> > -- net.inet.tcp.recvbuf_max
> >
> > -- net.inet.tcp.sendspace
> > -- net.inet.tcp.recvspace
> >
> > -- net.inet.tcp.delayed_ack
> >
> > - What threads/irq are allocated to your NIC? 'vmstat -i'
> >
> > - Are the above threads floating or mapped? 'cpuset -g ...'
> >
> > - Determine best settings for LRO/TSO for your card.
> >
> > - Disable nfs tcp drc
> >
> > - What is your atime setting?
> >
> >
> > If you really think you have a ZFS/Kernel issue, and you're
> > data fits in cache, dump ZFS, create a memory backed file system
> > and repeat your tests. This will purge a large portion of your
> > graph. LRO/TSO changes may do so also.
> >
> > You also state you are using a Linux client. Are you using
> > the MLX affinity scripts, buffer sizing suggestions, etc, etc.
> > Have you swapped the Linux system for a fbsd system?
> >
> > And as a final note, I regularly use Chelsio T62100 cards
> > in dual home and/or LACP environments in Supermicro boxes with 100's
> > of nfs boot (Bhyve, QEMU, and physical system) clients per server
> > with no network starvation or cpu bottlenecks. Clients boot, perform
> > their work, and then remotely request image rollback.
> >
> >
> > Hopefully the above will help and provide pointers.
> >
> > Cheers
> >
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