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[45.32.91.63]) by smtp.gmail.com with ESMTPSA id h12-20020a170902f7cc00b0017f778d4543sm14838978plw.241.2022.10.21.08.12.58 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 21 Oct 2022 08:12:59 -0700 (PDT) From: Zhenlei Huang Message-Id: Content-Type: multipart/alternative; boundary="Apple-Mail=_CE8B108F-F95C-4892-9C09-3F81D49101F6" 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 23:12:51 +0800 In-Reply-To: Cc: Michael Tuexen , freebsd-net@freebsd.org To: "Cui, Cheng" References: <75D35F36-7759-4168-ADBA-C2414F5B53BC@gmail.com> <712641B3-5196-40CC-9B64-04637F16F649@lurchi.franken.de> <62A0DD30-B3ED-48BE-9C01-146487599092@gmail.com> X-Mailer: Apple Mail (2.3608.120.23.2.7) X-Rspamd-Queue-Id: 4Mv7JG2b2lz3v6M X-Spamd-Bar: --- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=gmail.com header.s=20210112 header.b=QZhO7UIt; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (mx1.freebsd.org: domain of zlei.huang@gmail.com designates 2607:f8b0:4864:20::634 as permitted sender) smtp.mailfrom=zlei.huang@gmail.com X-Spamd-Result: default: False [-3.50 / 15.00]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; NEURAL_HAM_SHORT(-1.00)[-0.999]; DMARC_POLICY_ALLOW(-0.50)[gmail.com,none]; MV_CASE(0.50)[]; R_DKIM_ALLOW(-0.20)[gmail.com:s=20210112]; R_SPF_ALLOW(-0.20)[+ip6:2607:f8b0:4000::/36:c]; MIME_GOOD(-0.10)[multipart/alternative,text/plain]; FROM_HAS_DN(0.00)[]; DWL_DNSWL_NONE(0.00)[gmail.com:dkim]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; RCPT_COUNT_THREE(0.00)[3]; TO_MATCH_ENVRCPT_SOME(0.00)[]; PREVIOUSLY_DELIVERED(0.00)[freebsd-net@freebsd.org]; ASN(0.00)[asn:15169, ipnet:2607:f8b0::/32, country:US]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_IN_DNSWL_NONE(0.00)[2607:f8b0:4864:20::634:from]; RCVD_COUNT_THREE(0.00)[3]; FREEMAIL_FROM(0.00)[gmail.com]; TO_DN_SOME(0.00)[]; TAGGED_FROM(0.00)[]; DKIM_TRACE(0.00)[gmail.com:+]; RCVD_TLS_LAST(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FREEMAIL_ENVFROM(0.00)[gmail.com]; MIME_TRACE(0.00)[0:+,1:+,2:~]; MLMMJ_DEST(0.00)[freebsd-net@freebsd.org] X-ThisMailContainsUnwantedMimeParts: N --Apple-Mail=_CE8B108F-F95C-4892-9C09-3F81D49101F6 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 > On Oct 21, 2022, at 11:02 PM, Cui, Cheng > wrote: >=20 > You can also think about MacOS=E2=80=99s delayed ACK setup in default = is conservative. > =20 > https://developer.apple.com/forums/thread/716394 = I thinks that's a good = starting point. Thanks! > =20 > =20 > --=20 > Cheng Cui > =20 > From: owner-freebsd-net@freebsd.org = > on behalf of Zhenlei Huang = > > Date: Friday, October 21, 2022 at 11:01 AM > To: Michael Tuexen > > Cc: freebsd-net@freebsd.org = > > Subject: Re: Too aggressive TCP ACKs >=20 > NetApp Security WARNING: This is an external email. Do not click links = or open attachments unless you recognize the sender and know the content = is safe.=20 >=20 >=20 >=20 > =20 > 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! >=20 > 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. > =20 > 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. > =20 > Thanks! >=20 >=20 > Best regards > Michael >=20 >=20 >=20 >=20 > Best regards, > Zhenlei --Apple-Mail=_CE8B108F-F95C-4892-9C09-3F81D49101F6 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8
On = Oct 21, 2022, at 11:02 PM, Cui, Cheng <Cheng.Cui@netapp.com> wrote:

You can also think about MacOS=E2=80=99s delayed ACK = setup in default is conservative.
 
https://developer.apple.com/forums/thread/716394
I thinks that's a good starting = point.
Thanks!

 
 
-- 
Cheng Cui
 

From: owner-freebsd-net@freebsd.org <owner-freebsd-net@freebsd.org> on behalf of Zhenlei = Huang <zlei.huang@gmail.com>
Date: Friday, October 21, = 2022 at 11:01 AM
To: Michael Tuexen <michael.tuexen@lurchi.franken.de>
Cc: freebsd-net@freebsd.org <freebsd-net@freebsd.org>Subject: Re: Too aggressive TCP = ACKs

NetApp Security WARNING: = This is an external email. Do not click links or open attachments unless = you recognize the sender and know the content is safe. 



 
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=_CE8B108F-F95C-4892-9C09-3F81D49101F6--