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[45.32.91.63]) by smtp.gmail.com with ESMTPSA id z189-20020a6365c6000000b00429c5270710sm13247591pgb.1.2022.10.21.08.00.44 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 21 Oct 2022 08:00:46 -0700 (PDT) From: Zhenlei Huang Message-Id: <62A0DD30-B3ED-48BE-9C01-146487599092@gmail.com> Content-Type: multipart/alternative; boundary="Apple-Mail=_27F089CE-1845-4F54-89D4-5B235EF3B8C7" List-Id: Networking and TCP/IP with FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-net List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-net@freebsd.org Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.120.23.2.7\)) Subject: Re: Too aggressive TCP ACKs Date: Fri, 21 Oct 2022 23:00:39 +0800 In-Reply-To: <712641B3-5196-40CC-9B64-04637F16F649@lurchi.franken.de> Cc: freebsd-net@freebsd.org To: Michael Tuexen References: <75D35F36-7759-4168-ADBA-C2414F5B53BC@gmail.com> <712641B3-5196-40CC-9B64-04637F16F649@lurchi.franken.de> X-Mailer: Apple Mail (2.3608.120.23.2.7) X-Rspamd-Queue-Id: 4Mv7282zL2z3rts X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=gmail.com header.s=20210112 header.b=dpV8vFNG; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (mx1.freebsd.org: domain of zlei.huang@gmail.com designates 2607:f8b0:4864:20::630 as permitted sender) smtp.mailfrom=zlei.huang@gmail.com X-Spamd-Result: default: False [-2.50 / 15.00]; URI_COUNT_ODD(1.00)[5]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; NEURAL_HAM_SHORT(-1.00)[-1.000]; NEURAL_HAM_LONG(-1.00)[-1.000]; MV_CASE(0.50)[]; DMARC_POLICY_ALLOW(-0.50)[gmail.com,none]; R_SPF_ALLOW(-0.20)[+ip6:2607:f8b0:4000::/36:c]; R_DKIM_ALLOW(-0.20)[gmail.com:s=20210112]; MIME_GOOD(-0.10)[multipart/alternative,text/plain]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; FROM_HAS_DN(0.00)[]; DWL_DNSWL_NONE(0.00)[gmail.com:dkim]; PREVIOUSLY_DELIVERED(0.00)[freebsd-net@freebsd.org]; ASN(0.00)[asn:15169, ipnet:2607:f8b0::/32, country:US]; TO_MATCH_ENVRCPT_SOME(0.00)[]; TAGGED_FROM(0.00)[]; FREEMAIL_ENVFROM(0.00)[gmail.com]; RCVD_IN_DNSWL_NONE(0.00)[2607:f8b0:4864:20::630:from]; RCVD_COUNT_THREE(0.00)[3]; FREEMAIL_FROM(0.00)[gmail.com]; TO_DN_SOME(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; DKIM_TRACE(0.00)[gmail.com:+]; FROM_EQ_ENVFROM(0.00)[]; RCPT_COUNT_TWO(0.00)[2]; MIME_TRACE(0.00)[0:+,1:+,2:~]; RCVD_TLS_LAST(0.00)[]; MLMMJ_DEST(0.00)[freebsd-net@freebsd.org] X-ThisMailContainsUnwantedMimeParts: N --Apple-Mail=_27F089CE-1845-4F54-89D4-5B235EF3B8C7 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii > On Oct 21, 2022, at 10:34 PM, Michael Tuexen = > wrote: >=20 >> On 21. Oct 2022, at 16:19, Zhenlei Huang > wrote: >>=20 >> Hi, >>=20 >> While I was repeating = https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D258755 = , I observed = a >> strange behavior. The TCP ACKs from FreeBSD host are too aggressive. >>=20 >> My setup is simple: >> A B >> [ MacOS ] <=3D=3D=3D=3D> [ FreeBSD VM ] >> 192.168.120.1 192.168.12.134 (disable tso and lro) >> While A <--- B, i.e. A as server and B as client, the packets rate = looks good. >>=20 >> One session on B: >>=20 >> root@:~ # iperf3 -c 192.168.120.1 -b 10m >> Connecting to host 192.168.120.1, port 5201 >> [ 5] local 192.168.120.134 port 54459 connected to 192.168.120.1 = port 5201 >> [ ID] Interval Transfer Bitrate Retr Cwnd >> [ 5] 0.00-1.00 sec 1.25 MBytes 10.5 Mbits/sec 0 257 = KBytes =20 >> [ 5] 1.00-2.00 sec 1.25 MBytes 10.5 Mbits/sec 0 257 = KBytes =20 >> [ 5] 2.00-3.00 sec 1.12 MBytes 9.44 Mbits/sec 0 257 = KBytes =20 >> [ 5] 3.00-4.00 sec 1.25 MBytes 10.5 Mbits/sec 0 257 = KBytes =20 >> [ 5] 4.00-5.00 sec 1.12 MBytes 9.44 Mbits/sec 0 257 = KBytes =20 >> [ 5] 5.00-6.00 sec 1.25 MBytes 10.5 Mbits/sec 0 257 = KBytes =20 >> [ 5] 6.00-7.00 sec 1.12 MBytes 9.44 Mbits/sec 0 257 = KBytes =20 >> [ 5] 7.00-8.00 sec 1.25 MBytes 10.5 Mbits/sec 0 257 = KBytes =20 >> [ 5] 8.00-9.00 sec 1.12 MBytes 9.44 Mbits/sec 0 257 = KBytes =20 >> [ 5] 9.00-10.00 sec 1.25 MBytes 10.5 Mbits/sec 0 257 = KBytes =20 >> - - - - - - - - - - - - - - - - - - - - - - - - - >> [ ID] Interval Transfer Bitrate Retr >> [ 5] 0.00-10.00 sec 12.0 MBytes 10.1 Mbits/sec 0 = sender >> [ 5] 0.00-10.00 sec 12.0 MBytes 10.1 Mbits/sec = receiver >>=20 >> iperf Done. >>=20 >> Another session on B: >>=20 >> root@:~ # netstat -w 1 -I vmx0 >> input vmx0 output >> packets errs idrops bytes packets errs bytes colls >> 0 0 0 0 0 0 0 0 >> 0 0 0 0 0 0 0 0 >> 342 0 0 22600 526 0 775724 0 >> 150 0 0 9900 851 0 1281454 0 >> 109 0 0 7194 901 0 1357850 0 >> 126 0 0 8316 828 0 1246632 0 >> 122 0 0 8052 910 0 1370780 0 >> 109 0 0 7194 819 0 1233702 0 >> 120 0 0 7920 910 0 1370780 0 >> 110 0 0 7260 819 0 1233702 0 >> 123 0 0 8118 910 0 1370780 0 >> 109 0 0 7194 819 0 1233702 0 >> 73 0 0 5088 465 0 686342 0 >> 0 0 0 0 0 0 0 0 >> 0 0 0 0 0 0 0 0 >>=20 >>=20 >>=20 >> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D >>=20 >>=20 >> While A ---> B, i.e. A as client and B as server, the ACKs sent from = B looks strange. >>=20 >> Session on A: >>=20 >> % iperf3 -c 192.168.120.134 -b 10m >> Connecting to host 192.168.120.134, port 5201 >> [ 5] local 192.168.120.1 port 52370 connected to 192.168.120.134 = port 5201 >> [ ID] Interval Transfer Bitrate >> [ 5] 0.00-1.00 sec 1.25 MBytes 10.5 Mbits/sec =20= >> [ 5] 1.00-2.00 sec 1.25 MBytes 10.5 Mbits/sec =20= >> [ 5] 2.00-3.00 sec 1.12 MBytes 9.44 Mbits/sec =20= >> [ 5] 3.00-4.00 sec 1.25 MBytes 10.5 Mbits/sec =20= >> [ 5] 4.00-5.00 sec 1.12 MBytes 9.44 Mbits/sec =20= >> [ 5] 5.00-6.00 sec 1.25 MBytes 10.5 Mbits/sec =20= >> [ 5] 6.00-7.00 sec 1.12 MBytes 9.44 Mbits/sec =20= >> [ 5] 7.00-8.00 sec 1.25 MBytes 10.5 Mbits/sec =20= >> [ 5] 8.00-9.00 sec 1.12 MBytes 9.44 Mbits/sec =20= >> [ 5] 9.00-10.00 sec 1.25 MBytes 10.5 Mbits/sec =20= >> - - - - - - - - - - - - - - - - - - - - - - - - - >> [ ID] Interval Transfer Bitrate >> [ 5] 0.00-10.00 sec 12.0 MBytes 10.1 Mbits/sec = sender >> [ 5] 0.00-10.00 sec 12.0 MBytes 10.1 Mbits/sec = receiver >>=20 >> iperf Done. >>=20 >> Session on B: >>=20 >> root@:~ # netstat -w 1 -I vmx0 >> input vmx0 output >> packets errs idrops bytes packets errs bytes colls >> 0 0 0 0 0 0 0 0 >> 0 0 0 0 0 0 0 0 >> 649 0 0 960562 330 0 21800 0 >> 819 0 0 1233702 415 0 27390 0 >> 910 0 0 1370780 459 0 30294 0 >> 819 0 0 1233702 415 0 27390 0 >> 910 0 0 1370780 459 0 30294 0 >> 910 0 0 1370780 460 0 30360 0 >> 819 0 0 1233702 414 0 27324 0 >> 910 0 0 1370780 460 0 30360 0 >> 819 0 0 1233702 414 0 27324 0 >> 910 0 0 1370780 460 0 30360 0 >> 285 0 0 412287 147 0 9981 0 >> 0 0 0 0 0 0 0 0 >> 0 0 0 0 0 0 0 0 >> 0 0 0 0 0 0 0 0 >>=20 >>=20 >> The ACK packets replied from B (the FreeBSD VM) are too aggressive. = They are >> about one half of TCP packets received from A. >>=20 >> I've tested with different bitrates, from 10m to 300m, all behave the = same. >> Tested with baremetal FreeBSD 13.1 Box as B (with intel em driver), = the=20 >> bitrates is 1g, also behaves the same. >>=20 >> Also tried different FreeBSD versions, 11.4, 12.3, stable/13 and = current/14 all=20 >> behave the same. >>=20 >>=20 >> My question is, is that the expected behavior of current default TCP = stack? > That is what I would expect. TCP (on FreeBSD) is acking every other = packet. This > is also what is specified. MacOS, at least newer versions, send less = ACKs. Thanks for fast response! My have old memories about SACK which helps TCP performance. This = behavior seems odd from my mind. But those memories date back to 2008, that is 14 = years ago. The current implementation of TCP stack in FreeBSD head is too complexed = for me. Can you please point me the RFCs specifying this? So I can start over = with a quick glue. Thanks! >=20 > Best regards > Michael >>=20 >>=20 >>=20 >> Best regards, >> Zhenlei --Apple-Mail=_27F089CE-1845-4F54-89D4-5B235EF3B8C7 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii

On Oct 21, 2022, at 10:34 PM, Michael Tuexen = <michael.tuexen@lurchi.franken.de> wrote:

On = 21. Oct 2022, at 16:19, Zhenlei Huang <zlei.huang@gmail.com> wrote:

Hi,

While I was repeating https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D258755,= I observed a
strange behavior. The TCP ACKs from FreeBSD = host are too aggressive.

My setup is = simple:
        A =             &n= bsp;           &nbs= p;       B
  [ = MacOS ]  <=3D=3D=3D=3D> [ FreeBSD VM ]
192.168.120.1 =            192.168.= 12.134 (disable tso and lro)
While A <--- B, i.e. A as = server and B as client, the packets rate looks good.

One session on B:

root@:~ # = iperf3 -c 192.168.120.1 -b 10m
Connecting to host = 192.168.120.1, port 5201
[  5] local 192.168.120.134 = port 54459 connected to 192.168.120.1 port 5201
[ ID] = Interval =           Transfer =     Bitrate =         Retr  Cwnd
[  5]   0.00-1.00   sec  1.25 = MBytes  10.5 Mbits/sec    0    257 = KBytes       
[  5] =   1.00-2.00   sec  1.25 MBytes  10.5 = Mbits/sec    0    257 KBytes =       
[  5] =   2.00-3.00   sec  1.12 MBytes  9.44 = Mbits/sec    0    257 KBytes =       
[  5] =   3.00-4.00   sec  1.25 MBytes  10.5 = Mbits/sec    0    257 KBytes =       
[  5] =   4.00-5.00   sec  1.12 MBytes  9.44 = Mbits/sec    0    257 KBytes =       
[  5] =   5.00-6.00   sec  1.25 MBytes  10.5 = Mbits/sec    0    257 KBytes =       
[  5] =   6.00-7.00   sec  1.12 MBytes  9.44 = Mbits/sec    0    257 KBytes =       
[  5] =   7.00-8.00   sec  1.25 MBytes  10.5 = Mbits/sec    0    257 KBytes =       
[  5] =   8.00-9.00   sec  1.12 MBytes  9.44 = Mbits/sec    0    257 KBytes =       
[  5] =   9.00-10.00  sec  1.25 MBytes  10.5 Mbits/sec =    0    257 KBytes =       
- - - - - - - - - - - = - - - - - - - - - - - - - -
[ ID] Interval =           Transfer =     Bitrate =         Retr
[ =  5]   0.00-10.00  sec  12.0 MBytes  10.1 = Mbits/sec    0 =             se= nder
[  5]   0.00-10.00  sec =  12.0 MBytes  10.1 Mbits/sec =             &n= bsp;    receiver

iperf = Done.

Another session on B:
root@:~ # netstat -w 1 -I vmx0
          &nb= sp;input =           vmx0 =           output
  packets  errs idrops =      bytes    packets  errs =      bytes colls
        0 =     0     0 =          0 =          0 =     0 =          0 =     0
        0 =     0     0 =          0 =          0 =     0 =          0 =     0
      342 =     0     0 =      22600 =        526     0 =     775724     0
      150 =     0     0 =       9900 =        851     0 =    1281454     0
      109 =     0     0 =       7194 =        901     0 =    1357850     0
      126 =     0     0 =       8316 =        828     0 =    1246632     0
      122 =     0     0 =       8052 =        910     0 =    1370780     0
      109 =     0     0 =       7194 =        819     0 =    1233702     0
      120 =     0     0 =       7920 =        910     0 =    1370780     0
      110 =     0     0 =       7260 =        819     0 =    1233702     0
      123 =     0     0 =       8118 =        910     0 =    1370780     0
      109 =     0     0 =       7194 =        819     0 =    1233702     0
       73 =     0     0 =       5088 =        465     0 =     686342     0
        0 =     0     0 =          0 =          0 =     0 =          0 =     0
        0 =     0     0 =          0 =          0 =     0 =          0 =     0



=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D


While A ---> B, i.e. A as client and B as = server, the ACKs sent from B looks strange.

Session on A:

% iperf3 -c = 192.168.120.134 -b 10m
Connecting to host 192.168.120.134, = port 5201
[  5] local 192.168.120.1 port 52370 = connected to 192.168.120.134 port 5201
[ ID] Interval =           Transfer =     Bitrate
[  5] =   0.00-1.00   sec  1.25 MBytes  10.5 = Mbits/sec =             &n= bsp;    
[  5] =   1.00-2.00   sec  1.25 MBytes  10.5 = Mbits/sec =             &n= bsp;    
[  5] =   2.00-3.00   sec  1.12 MBytes  9.44 = Mbits/sec =             &n= bsp;    
[  5] =   3.00-4.00   sec  1.25 MBytes  10.5 = Mbits/sec =             &n= bsp;    
[  5] =   4.00-5.00   sec  1.12 MBytes  9.44 = Mbits/sec =             &n= bsp;    
[  5] =   5.00-6.00   sec  1.25 MBytes  10.5 = Mbits/sec =             &n= bsp;    
[  5] =   6.00-7.00   sec  1.12 MBytes  9.44 = Mbits/sec =             &n= bsp;    
[  5] =   7.00-8.00   sec  1.25 MBytes  10.5 = Mbits/sec =             &n= bsp;    
[  5] =   8.00-9.00   sec  1.12 MBytes  9.44 = Mbits/sec =             &n= bsp;    
[  5] =   9.00-10.00  sec  1.25 MBytes  10.5 Mbits/sec =             &n= bsp;    
- - - - - - - - - - - - - - - = - - - - - - - - - -
[ ID] Interval =           Transfer =     Bitrate
[  5] =   0.00-10.00  sec  12.0 MBytes  10.1 Mbits/sec =             &n= bsp;    sender
[  5] =   0.00-10.00  sec  12.0 MBytes  10.1 Mbits/sec =             &n= bsp;    receiver

iperf = Done.

Session on B:

root@:~ # netstat -w 1 -I vmx0
          &nb= sp;input =           vmx0 =           output
  packets  errs idrops =      bytes    packets  errs =      bytes colls
        0 =     0     0 =          0 =          0 =     0 =          0 =     0
        0 =     0     0 =          0 =          0 =     0 =          0 =     0
      649 =     0     0 =     960562 =        330     0 =      21800     0
      819 =     0     0 =    1233702        415 =     0      27390 =     0
      910 =     0     0 =    1370780        459 =     0      30294 =     0
      819 =     0     0 =    1233702        415 =     0      27390 =     0
      910 =     0     0 =    1370780        459 =     0      30294 =     0
      910 =     0     0 =    1370780        460 =     0      30360 =     0
      819 =     0     0 =    1233702        414 =     0      27324 =     0
      910 =     0     0 =    1370780        460 =     0      30360 =     0
      819 =     0     0 =    1233702        414 =     0      27324 =     0
      910 =     0     0 =    1370780        460 =     0      30360 =     0
      285 =     0     0 =     412287 =        147     0 =       9981     0
        0 =     0     0 =          0 =          0 =     0 =          0 =     0
        0 =     0     0 =          0 =          0 =     0 =          0 =     0
        0 =     0     0 =          0 =          0 =     0 =          0 =     0


The = ACK packets replied from B (the FreeBSD VM) are too aggressive. They = are
about one half of TCP packets received from A.

I've tested with different bitrates, from 10m = to 300m, all behave the same.
Tested with baremetal = FreeBSD 13.1 Box as B (with intel em driver), the 
bitrates is = 1g, also  behaves the same.

Also tried = different FreeBSD versions, 11.4, 12.3, stable/13 and current/14 = all 
behave the same.


My= question is, is that the expected behavior of current default TCP = stack?
That is what I would expect. TCP (on FreeBSD) is acking every = other packet. This
is also what is specified. MacOS, at least newer versions, = send less ACKs.
Thanks for = fast response!

My have old memories about SACK which = helps TCP performance. This behavior
seems odd from my mind. = But those memories date back to 2008, that is 14 years = ago.

The current = implementation of TCP stack in FreeBSD head is too complexed for = me.
Can you please point me the RFCs specifying this? So I can = start over with a quick glue.

Thanks!

Best regards
Michael



Best regards,
Zhenlei

= --Apple-Mail=_27F089CE-1845-4F54-89D4-5B235EF3B8C7--