Date: Wed, 23 May 2007 03:02:26 GMT From: Phil Rosenthal<pr@isprime.com> To: freebsd-gnats-submit@FreeBSD.org Subject: bin/112881: systat -tcp does not show tcp rexmit on sack enabled sockets (patch included) Message-ID: <200705230302.l4N32Q5N067196@www.freebsd.org> Resent-Message-ID: <200705230310.l4N3A3Y7022233@freefall.freebsd.org>
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>Number: 112881 >Category: bin >Synopsis: systat -tcp does not show tcp rexmit on sack enabled sockets (patch included) >Confidential: no >Severity: non-critical >Priority: low >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: update >Submitter-Id: current-users >Arrival-Date: Wed May 23 03:10:02 GMT 2007 >Closed-Date: >Last-Modified: >Originator: Phil Rosenthal >Release: FreeBSD 6.2-STABLE amd64 >Organization: ISPrime LLC >Environment: FreeBSD bmw2.isprime.com 6.2-STABLE FreeBSD 6.2-STABLE #0: Tue May 22 22:20:23 EDT 2007 root@bmw2.isprime.com:/usr/obj/usr/src/sys/BMW2 amd64 >Description: FreeBSD's "systat" tool has a mode to display statistics for all tcp sessions on the system. This mode is called by running "systat -tcp". When a packet is retransmitted due to duplicate ack packets, or a timeout waiting for an ack, tcps_sndrexmitpack is incremented. When a packet is retransmitted due to a selective acknowledgement (sack), tcps_sack_rexmits is incremented instead. systat -tcp only shows tcps_sndrexmitpack, and given that most clients today support sack, the user is falsely informed that there is a much lower amount of packet loss/retransmits. Additionally, the 9 digit values are easily overflowed on a server serving hundreds of megabits of traffic which is becoming more commonplace given the performance and wide availability of gig-e chipsets. The patch referenced below fixes both of these issues. >How-To-Repeat: 1) Enable sack on both a client and a server, and set up a tcp socket. 2) Cause packet loss (you can use dummynet for this) 3) Watch systat -tcp >Fix: cd /usr/src/usr.bin/systat fetch http://bmw2.isprime.com/systat-sack-rexmit.diff patch < systat-sack-rexmit.diff make make install This patch is built against FreeBSD 6.2-STABLE. Earlier builds will fail with this patch. Patch attached with submission follows: --- tcp.c-ol Tue May 22 19:03:11 2007 +++ tcp.c Tue May 22 19:23:59 2007 @@ -71,25 +71,26 @@ --0 1 2 3 4 5 6 7 --0123456789012345678901234567890123456789012345678901234567890123456789012345 00 TCP Connections TCP Packets -01999999999 connections initiated 999999999 total packets sent -02999999999 connections accepted 999999999 - data -03999999999 connections established 999999999 - data (retransmit) -04999999999 connections dropped 999999999 - ack-only -05999999999 - in embryonic state 999999999 - window probes -06999999999 - on retransmit timeout 999999999 - window updates -07999999999 - by keepalive 999999999 - urgent data only -08999999999 - from listen queue 999999999 - control -09 999999999 - resends by PMTU discovery -10 TCP Timers 999999999 total packets received -11999999999 potential rtt updates 999999999 - in sequence -12999999999 - successful 999999999 - completely duplicate -13999999999 delayed acks sent 999999999 - with some duplicate data -14999999999 retransmit timeouts 999999999 - out-of-order -15999999999 persist timeouts 999999999 - duplicate acks -16999999999 keepalive probes 999999999 - acks -17999999999 - timeouts 999999999 - window probes -18 999999999 - window updates -19 999999999 - bad checksum +01999999999999 connections initiated 999999999999 total packets sent +02999999999999 connections accepted 999999999999 - data +03999999999999 connections established 999999999999 - data (retransmit by dupack) +04999999999999 connections dropped 999999999999 - data (retransmit by sack) +05999999999999 - in embryonic state 999999999999 - ack-only +06999999999999 - on retransmit timeout 999999999999 - window probes +07999999999999 - by keepalive 999999999999 - window updates +08999999999999 - from listen queue 999999999999 - urgent data only +09 999999999999 - control +10 TCP Timers 999999999999 resends by PMTU discovery +11999999999999 potential rtt updates 999999999999 - total packets received +12999999999999 - successful 999999999999 - in sequence +13999999999999 delayed acks sent 999999999999 - completely duplicate +14999999999999 retransmit timeouts 999999999999 - with some duplicate data +15999999999999 persist timeouts 999999999999 - out-of-order +16999999999999 keepalive probes 999999999999 - duplicate acks +17999999999999 - timeouts 999999999999 - acks +18 999999999999 - window probes +19 999999999999 - window updates +20 999999999999 - bad checksum --0123456789012345678901234567890123456789012345678901234567890123456789012345 --0 1 2 3 4 5 6 7 */ @@ -115,28 +116,29 @@ labeltcp(void) { wmove(wnd, 0, 0); wclrtoeol(wnd); -#define L(row, str) mvwprintw(wnd, row, 10, str) -#define R(row, str) mvwprintw(wnd, row, 45, str); +#define L(row, str) mvwprintw(wnd, row, 13, str) +#define R(row, str) mvwprintw(wnd, row, 48, str); L(0, "TCP Connections"); R(0, "TCP Packets"); L(1, "connections initiated"); R(1, "total packets sent"); L(2, "connections accepted"); R(2, "- data"); L(3, "connections established"); R(3, "- data (retransmit)"); - L(4, "connections dropped"); R(4, "- ack-only"); - L(5, "- in embryonic state"); R(5, "- window probes"); - L(6, "- on retransmit timeout"); R(6, "- window updates"); - L(7, "- by keepalive"); R(7, "- urgent data only"); - L(8, "- from listen queue"); R(8, "- control"); - R(9, "- resends by PMTU discovery"); - L(10, "TCP Timers"); R(10, "total packets received"); - L(11, "potential rtt updates"); R(11, "- in sequence"); - L(12, "- successful"); R(12, "- completely duplicate"); - L(13, "delayed acks sent"); R(13, "- with some duplicate data"); - L(14, "retransmit timeouts"); R(14, "- out-of-order"); - L(15, "persist timeouts"); R(15, "- duplicate acks"); - L(16, "keepalive probes"); R(16, "- acks"); - L(17, "- timeouts"); R(17, "- window probes"); - R(18, "- window updates"); - R(19, "- bad checksum"); + L(4, "connections dropped"); R(4, "- data (retransmit by sack)"); + L(5, "- in embryonic state"); R(5, "- ack-only"); + L(6, "- on retransmit timeout"); R(6, "- window probes"); + L(7, "- by keepalive"); R(7, "- window updates"); + L(8, "- from listen queue"); R(8, "- urgent data only"); + R(9, "- control"); + L(10, "TCP Timers"); R(10, "- resends by PMTU discovery"); + L(11, "potential rtt updates"); R(11, "total packets received"); + L(12, "- successful"); R(12, "- in sequence"); + L(13, "delayed acks sent"); R(13, "- completely duplicate"); + L(14, "retransmit timeouts"); R(14, "- with some duplicate data"); + L(15, "persist timeouts"); R(15, "- out-of-order"); + L(16, "keepalive probes"); R(16, "- duplicate acks"); + L(17, "- timeouts"); R(17, "- acks"); + R(18, "- window probes"); + R(19, "- window updates"); + R(20, "- bad checksum"); #undef L #undef R } @@ -183,6 +185,7 @@ DO(tcps_sndpack); DO(tcps_sndbyte); DO(tcps_sndrexmitpack); + DO(tcps_sack_rexmits); DO(tcps_sndrexmitbyte); DO(tcps_sndacks); DO(tcps_sndprobe); @@ -237,28 +240,29 @@ domode(&stats); #define DO(stat, row, col) \ - mvwprintw(wnd, row, col, "%9lu", stats.stat) + mvwprintw(wnd, row, col, "%12lu", stats.stat) #define L(row, stat) DO(stat, row, 0) #define R(row, stat) DO(stat, row, 35) L(1, tcps_connattempt); R(1, tcps_sndtotal); L(2, tcps_accepts); R(2, tcps_sndpack); L(3, tcps_connects); R(3, tcps_sndrexmitpack); - L(4, tcps_drops); R(4, tcps_sndacks); - L(5, tcps_conndrops); R(5, tcps_sndprobe); - L(6, tcps_timeoutdrop); R(6, tcps_sndwinup); - L(7, tcps_keepdrops); R(7, tcps_sndurg); - L(8, tcps_listendrop); R(8, tcps_sndctrl); - R(9, tcps_mturesent); - R(10, tcps_rcvtotal); - L(11, tcps_segstimed); R(11, tcps_rcvpack); - L(12, tcps_rttupdated); R(12, tcps_rcvduppack); - L(13, tcps_delack); R(13, tcps_rcvpartduppack); - L(14, tcps_rexmttimeo); R(14, tcps_rcvoopack); - L(15, tcps_persisttimeo); R(15, tcps_rcvdupack); - L(16, tcps_keepprobe); R(16, tcps_rcvackpack); - L(17, tcps_keeptimeo); R(17, tcps_rcvwinprobe); - R(18, tcps_rcvwinupd); - R(19, tcps_rcvbadsum); + L(4, tcps_drops); R(4, tcps_sack_rexmits); + L(5, tcps_conndrops); R(5, tcps_sndacks); + L(6, tcps_timeoutdrop); R(6, tcps_sndprobe); + L(7, tcps_keepdrops); R(7, tcps_sndwinup); + L(8, tcps_listendrop); R(8, tcps_sndurg); + R(9, tcps_sndctrl); + R(10, tcps_mturesent); + L(11, tcps_segstimed); R(11, tcps_rcvtotal); + L(12, tcps_rttupdated); R(12, tcps_rcvpack); + L(13, tcps_delack); R(13, tcps_rcvduppack); + L(14, tcps_rexmttimeo); R(14, tcps_rcvpartduppack); + L(15, tcps_persisttimeo); R(15, tcps_rcvoopack); + L(16, tcps_keepprobe); R(16, tcps_rcvdupack); + L(17, tcps_keeptimeo); R(17, tcps_rcvackpack); + R(18, tcps_rcvwinprobe); + R(19, tcps_rcvwinupd); + R(20, tcps_rcvbadsum); #undef DO #undef L #undef R >Release-Note: >Audit-Trail: >Unformatted:
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