Date: Fri, 21 Oct 2022 23:12:51 +0800 From: Zhenlei Huang <zlei.huang@gmail.com> To: "Cui, Cheng" <Cheng.Cui@netapp.com> Cc: Michael Tuexen <michael.tuexen@lurchi.franken.de>, freebsd-net@freebsd.org Subject: Re: Too aggressive TCP ACKs Message-ID: <E7BD2488-940B-42E5-8C53-F420DA8F2283@gmail.com> In-Reply-To: <MN2PR06MB6237E90881035621441597989D2D9@MN2PR06MB6237.namprd06.prod.outlook.com> References: <75D35F36-7759-4168-ADBA-C2414F5B53BC@gmail.com> <712641B3-5196-40CC-9B64-04637F16F649@lurchi.franken.de> <62A0DD30-B3ED-48BE-9C01-146487599092@gmail.com> <MN2PR06MB6237E90881035621441597989D2D9@MN2PR06MB6237.namprd06.prod.outlook.com>
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[-- Attachment #1 --] > On Oct 21, 2022, at 11:02 PM, Cui, Cheng <Cheng.Cui@netapp.com <mailto:Cheng.Cui@netapp.com>> wrote: > > You can also think about MacOS’s delayed ACK setup in default is conservative. > > https://developer.apple.com/forums/thread/716394 <https://developer.apple.com/forums/thread/716394>I thinks that's a good starting point. Thanks! > > > -- > Cheng Cui > > From: owner-freebsd-net@freebsd.org <mailto:owner-freebsd-net@freebsd.org> <owner-freebsd-net@freebsd.org <mailto:owner-freebsd-net@freebsd.org>> on behalf of Zhenlei Huang <zlei.huang@gmail.com <mailto:zlei.huang@gmail.com>> > Date: Friday, October 21, 2022 at 11:01 AM > To: Michael Tuexen <michael.tuexen@lurchi.franken.de <mailto:michael.tuexen@lurchi.franken.de>> > Cc: freebsd-net@freebsd.org <mailto:freebsd-net@freebsd.org> <freebsd-net@freebsd.org <mailto: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 <mailto:michael.tuexen@lurchi.franken.de>> wrote: > > On 21. Oct 2022, at 16:19, Zhenlei Huang <zlei.huang@gmail.com <mailto:zlei.huang@gmail.com>> wrote: > > Hi, > > While I was repeating https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=258755 <https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=258755>, I observed a > strange behavior. The TCP ACKs from FreeBSD host are too aggressive. > > My setup is simple: > A B > [ MacOS ] <====> [ 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 sender > [ 5] 0.00-10.00 sec 12.0 MBytes 10.1 Mbits/sec receiver > > iperf Done. > > Another session on B: > > 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 > > > > ================================================================ > > > 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 > [ 5] 1.00-2.00 sec 1.25 MBytes 10.5 Mbits/sec > [ 5] 2.00-3.00 sec 1.12 MBytes 9.44 Mbits/sec > [ 5] 3.00-4.00 sec 1.25 MBytes 10.5 Mbits/sec > [ 5] 4.00-5.00 sec 1.12 MBytes 9.44 Mbits/sec > [ 5] 5.00-6.00 sec 1.25 MBytes 10.5 Mbits/sec > [ 5] 6.00-7.00 sec 1.12 MBytes 9.44 Mbits/sec > [ 5] 7.00-8.00 sec 1.25 MBytes 10.5 Mbits/sec > [ 5] 8.00-9.00 sec 1.12 MBytes 9.44 Mbits/sec > [ 5] 9.00-10.00 sec 1.25 MBytes 10.5 Mbits/sec > - - - - - - - - - - - - - - - - - - - - - - - - - > [ 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 > > iperf Done. > > Session on B: > > 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 > > > 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 [-- Attachment #2 --] <html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Oct 21, 2022, at 11:02 PM, Cui, Cheng <<a href="mailto:Cheng.Cui@netapp.com" class="">Cheng.Cui@netapp.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="WordSection1" style="page: WordSection1; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">You can also think about MacOS’s delayed ACK setup in default is conservative.<o:p class=""></o:p></span></div><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""><o:p class=""> </o:p></span></div><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""><a href="https://developer.apple.com/forums/thread/716394" style="color: blue; text-decoration: underline;" class="">https://developer.apple.com/forums/thread/716394</a></span></div></div></div></blockquote><div>I thinks that's a good starting point.</div><div>Thanks!</div><br class=""><blockquote type="cite" class=""><div class=""><div class="WordSection1" style="page: WordSection1; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""><o:p class=""></o:p></span></div><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""><o:p class=""> </o:p></span></div><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""><o:p class=""> </o:p></span></div><div class=""><div class=""><div class=""><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">-- <o:p class=""></o:p></span></div></div></div></div><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">Cheng Cui</span><span style="font-size: 11pt;" class=""><o:p class=""></o:p></span></div><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""><o:p class=""> </o:p></span></div><div style="border-style: solid none none; border-top-width: 1pt; border-top-color: rgb(181, 196, 223); padding: 3pt 0in 0in;" class=""><p class="MsoNormal" style="margin: 0in 0in 12pt; font-size: 10pt; font-family: Calibri, sans-serif;"><b class=""><span style="font-size: 12pt;" class="">From:<span class="Apple-converted-space"> </span></span></b><span style="font-size: 12pt;" class=""><a href="mailto:owner-freebsd-net@freebsd.org" style="color: blue; text-decoration: underline;" class="">owner-freebsd-net@freebsd.org</a><span class="Apple-converted-space"> </span><<a href="mailto:owner-freebsd-net@freebsd.org" style="color: blue; text-decoration: underline;" class="">owner-freebsd-net@freebsd.org</a>> on behalf of Zhenlei Huang <<a href="mailto:zlei.huang@gmail.com" style="color: blue; text-decoration: underline;" class="">zlei.huang@gmail.com</a>><br class=""><b class="">Date:<span class="Apple-converted-space"> </span></b>Friday, October 21, 2022 at 11:01 AM<br class=""><b class="">To:<span class="Apple-converted-space"> </span></b>Michael Tuexen <<a href="mailto:michael.tuexen@lurchi.franken.de" style="color: blue; text-decoration: underline;" class="">michael.tuexen@lurchi.franken.de</a>><br class=""><b class="">Cc:<span class="Apple-converted-space"> </span></b><a href="mailto:freebsd-net@freebsd.org" style="color: blue; text-decoration: underline;" class="">freebsd-net@freebsd.org</a><span class="Apple-converted-space"> </span><<a href="mailto:freebsd-net@freebsd.org" style="color: blue; text-decoration: underline;" class="">freebsd-net@freebsd.org</a>><br class=""><b class="">Subject:<span class="Apple-converted-space"> </span></b>Re: Too aggressive TCP ACKs<o:p class=""></o:p></span></p></div><table class="MsoNormalTable" border="1" cellspacing="0" cellpadding="0" align="left" width="200" style="width: 150pt; background-color: rgb(0, 103, 197); background-position: initial initial; background-repeat: initial initial;"><tbody class=""><tr class=""><td nowrap="" style="padding: 7.5pt;" class=""><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><b class=""><span style="font-family: Arial, sans-serif; color: yellow;" class="">NetApp Security WARNING</span></b><span style="font-family: Arial, sans-serif; color: yellow;" class="">: This is an external email. Do not click links or open attachments unless you recognize the sender and know the content is safe.<span class="Apple-converted-space"> </span></span><span style="font-size: 11pt;" class=""><o:p class=""></o:p></span></div></td></tr></tbody></table><p class="MsoNormal" style="margin: 0in 0in 12pt; font-size: 10pt; font-family: Calibri, sans-serif;"><span style="font-size: 11pt;" class=""><br class=""><br class=""><o:p class=""></o:p></span></p><div class=""><div class=""><div class=""><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""><o:p class=""> </o:p></span></div></div></div><div class=""><blockquote style="margin-top: 5pt; margin-bottom: 5pt;" class=""><div class=""><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">On Oct 21, 2022, at 10:34 PM, Michael Tuexen <<a href="mailto:michael.tuexen@lurchi.franken.de" style="color: blue; text-decoration: underline;" class="">michael.tuexen@lurchi.franken.de</a>> wrote:<o:p class=""></o:p></span></div></div><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""><o:p class=""> </o:p></span></div><div class=""><blockquote style="margin-top: 5pt; margin-bottom: 5pt; font-variant-caps: normal; text-align: start; -webkit-text-stroke-width: 0px; word-spacing: 0px;" class=""><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 9pt; font-family: Helvetica;" class="">On 21. Oct 2022, at 16:19, Zhenlei Huang <<a href="mailto:zlei.huang@gmail.com" style="color: blue; text-decoration: underline;" class="">zlei.huang@gmail.com</a>> wrote:<br class=""><br class="">Hi,<br class=""><br class="">While I was repeating<span class="Apple-converted-space"> </span><a href="https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=258755" style="color: blue; text-decoration: underline;" class="">https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=258755</a>, I observed a<br class="">strange behavior. The TCP ACKs from FreeBSD host are too aggressive.<br class=""><br class="">My setup is simple:<br class=""> A B<br class=""> [ MacOS ] <====> [ FreeBSD VM ]<br class="">192.168.120.1 192.168.12.134 (disable tso and lro)<br class="">While A <--- B, i.e. A as server and B as client, the packets rate looks good.<br class=""><br class="">One session on B:<br class=""><br class="">root@:~ # iperf3 -c 192.168.120.1 -b 10m<br class="">Connecting to host 192.168.120.1, port 5201<br class="">[ 5] local 192.168.120.134 port 54459 connected to 192.168.120.1 port 5201<br class="">[ ID] Interval Transfer Bitrate Retr Cwnd<br class="">[ 5] 0.00-1.00 sec 1.25 MBytes 10.5 Mbits/sec 0 257 KBytes <br class="">[ 5] 1.00-2.00 sec 1.25 MBytes 10.5 Mbits/sec 0 257 KBytes <br class="">[ 5] 2.00-3.00 sec 1.12 MBytes 9.44 Mbits/sec 0 257 KBytes <br class="">[ 5] 3.00-4.00 sec 1.25 MBytes 10.5 Mbits/sec 0 257 KBytes <br class="">[ 5] 4.00-5.00 sec 1.12 MBytes 9.44 Mbits/sec 0 257 KBytes <br class="">[ 5] 5.00-6.00 sec 1.25 MBytes 10.5 Mbits/sec 0 257 KBytes <br class="">[ 5] 6.00-7.00 sec 1.12 MBytes 9.44 Mbits/sec 0 257 KBytes <br class="">[ 5] 7.00-8.00 sec 1.25 MBytes 10.5 Mbits/sec 0 257 KBytes <br class="">[ 5] 8.00-9.00 sec 1.12 MBytes 9.44 Mbits/sec 0 257 KBytes <br class="">[ 5] 9.00-10.00 sec 1.25 MBytes 10.5 Mbits/sec 0 257 KBytes <br class="">- - - - - - - - - - - - - - - - - - - - - - - - -<br class="">[ ID] Interval Transfer Bitrate Retr<br class="">[ 5] 0.00-10.00 sec 12.0 MBytes 10.1 Mbits/sec 0 sender<br class="">[ 5] 0.00-10.00 sec 12.0 MBytes 10.1 Mbits/sec receiver<br class=""><br class="">iperf Done.<br class=""><br class="">Another session on B:<br class=""><br class="">root@:~ # netstat -w 1 -I vmx0<br class=""> input vmx0 output<br class=""> packets errs idrops bytes packets errs bytes colls<br class=""> 0 0 0 0 0 0 0 0<br class=""> 0 0 0 0 0 0 0 0<br class=""> 342 0 0 22600 526 0 775724 0<br class=""> 150 0 0 9900 851 0 1281454 0<br class=""> 109 0 0 7194 901 0 1357850 0<br class=""> 126 0 0 8316 828 0 1246632 0<br class=""> 122 0 0 8052 910 0 1370780 0<br class=""> 109 0 0 7194 819 0 1233702 0<br class=""> 120 0 0 7920 910 0 1370780 0<br class=""> 110 0 0 7260 819 0 1233702 0<br class=""> 123 0 0 8118 910 0 1370780 0<br class=""> 109 0 0 7194 819 0 1233702 0<br class=""> 73 0 0 5088 465 0 686342 0<br class=""> 0 0 0 0 0 0 0 0<br class=""> 0 0 0 0 0 0 0 0<br class=""><br class=""><br class=""><br class="">================================================================<br class=""><br class=""><br class="">While A ---> B, i.e. A as client and B as server, the ACKs sent from B looks strange.<br class=""><br class="">Session on A:<br class=""><br class="">% iperf3 -c 192.168.120.134 -b 10m<br class="">Connecting to host 192.168.120.134, port 5201<br class="">[ 5] local 192.168.120.1 port 52370 connected to 192.168.120.134 port 5201<br class="">[ ID] Interval Transfer Bitrate<br class="">[ 5] 0.00-1.00 sec 1.25 MBytes 10.5 Mbits/sec <br class="">[ 5] 1.00-2.00 sec 1.25 MBytes 10.5 Mbits/sec <br class="">[ 5] 2.00-3.00 sec 1.12 MBytes 9.44 Mbits/sec <br class="">[ 5] 3.00-4.00 sec 1.25 MBytes 10.5 Mbits/sec <br class="">[ 5] 4.00-5.00 sec 1.12 MBytes 9.44 Mbits/sec <br class="">[ 5] 5.00-6.00 sec 1.25 MBytes 10.5 Mbits/sec <br class="">[ 5] 6.00-7.00 sec 1.12 MBytes 9.44 Mbits/sec <br class="">[ 5] 7.00-8.00 sec 1.25 MBytes 10.5 Mbits/sec <br class="">[ 5] 8.00-9.00 sec 1.12 MBytes 9.44 Mbits/sec <br class="">[ 5] 9.00-10.00 sec 1.25 MBytes 10.5 Mbits/sec <br class="">- - - - - - - - - - - - - - - - - - - - - - - - -<br class="">[ ID] Interval Transfer Bitrate<br class="">[ 5] 0.00-10.00 sec 12.0 MBytes 10.1 Mbits/sec sender<br class="">[ 5] 0.00-10.00 sec 12.0 MBytes 10.1 Mbits/sec receiver<br class=""><br class="">iperf Done.<br class=""><br class="">Session on B:<br class=""><br class="">root@:~ # netstat -w 1 -I vmx0<br class=""> input vmx0 output<br class=""> packets errs idrops bytes packets errs bytes colls<br class=""> 0 0 0 0 0 0 0 0<br class=""> 0 0 0 0 0 0 0 0<br class=""> 649 0 0 960562 330 0 21800 0<br class=""> 819 0 0 1233702 415 0 27390 0<br class=""> 910 0 0 1370780 459 0 30294 0<br class=""> 819 0 0 1233702 415 0 27390 0<br class=""> 910 0 0 1370780 459 0 30294 0<br class=""> 910 0 0 1370780 460 0 30360 0<br class=""> 819 0 0 1233702 414 0 27324 0<br class=""> 910 0 0 1370780 460 0 30360 0<br class=""> 819 0 0 1233702 414 0 27324 0<br class=""> 910 0 0 1370780 460 0 30360 0<br class=""> 285 0 0 412287 147 0 9981 0<br class=""> 0 0 0 0 0 0 0 0<br class=""> 0 0 0 0 0 0 0 0<br class=""> 0 0 0 0 0 0 0 0<br class=""><br class=""><br class="">The ACK packets replied from B (the FreeBSD VM) are too aggressive. They are<br class="">about one half of TCP packets received from A.<br class=""><br class="">I've tested with different bitrates, from 10m to 300m, all behave the same.<br class="">Tested with baremetal FreeBSD 13.1 Box as B (with intel em driver), the<span class="apple-converted-space"> </span><br class="">bitrates is 1g, also behaves the same.<br class=""><br class="">Also tried different FreeBSD versions, 11.4, 12.3, stable/13 and current/14 all<span class="apple-converted-space"> </span><br class="">behave the same.<br class=""><br class=""><br class="">My question is, is that the expected behavior of current default TCP stack?<o:p class=""></o:p></span></div></blockquote><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 9pt; font-family: Helvetica;" class="">That is what I would expect. TCP (on FreeBSD) is acking every other packet. This<br class="">is also what is specified. MacOS, at least newer versions, send less ACKs.</span><span style="font-size: 11pt;" class=""><o:p class=""></o:p></span></div></div></blockquote><div class=""><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">Thanks for fast response!<o:p class=""></o:p></span></div></div><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""><br class="">My have old memories about SACK which helps TCP performance. This behavior<o:p class=""></o:p></span></div></div><div class=""><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">seems odd from my mind. But those <span style="" class="">memories date back to 2008, that is 14 years ago.</span><o:p class=""></o:p></span></div></div><div class=""><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""><o:p class=""> </o:p></span></div></div><div class=""><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">The current implementation of TCP stack in FreeBSD head is too complexed for me.<o:p class=""></o:p></span></div></div><div class=""><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">Can you please point me the RFCs specifying this? So I can start over with a quick glue.<o:p class=""></o:p></span></div></div><div class=""><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""><o:p class=""> </o:p></span></div></div><div class=""><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">Thanks!<br class=""><br class=""><o:p class=""></o:p></span></div><blockquote style="margin-top: 5pt; margin-bottom: 5pt;" class=""><div class=""><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 9pt; font-family: Helvetica;" class=""><br class="">Best regards<br class="">Michael<br style="caret-color: rgb(0, 0, 0); font-variant-caps: normal; text-align: start; -webkit-text-stroke-width: 0px; word-spacing: 0px;" class=""><br class=""></span><span style="font-size: 11pt;" class=""><o:p class=""></o:p></span></div><blockquote style="margin-top: 5pt; margin-bottom: 5pt;" class=""><div style="margin: 0in; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 9pt; font-family: Helvetica;" class=""><br class=""><br class=""><br class="">Best regards,<br class="">Zhenlei</span></div></blockquote></div></blockquote></div></div></div></div></blockquote></div><br class=""></body></html>
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