Date: Mon, 15 Aug 2011 16:37:20 GMT From: Darren Baginski <kickbsd@yandex.ru> To: freebsd-gnats-submit@FreeBSD.org Subject: kern/159795: excessive duplicate ACKs and TCP session freezes Message-ID: <201108151637.p7FGbKpm073453@red.freebsd.org> Resent-Message-ID: <201108151640.p7FGe4jj025585@freefall.freebsd.org>
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>Number: 159795 >Category: kern >Synopsis: excessive duplicate ACKs and TCP session freezes >Confidential: no >Severity: critical >Priority: high >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Mon Aug 15 16:40:03 UTC 2011 >Closed-Date: >Last-Modified: >Originator: Darren Baginski >Release: 8.2-RELEASE >Organization: N/A >Environment: FreeBSD downloader1.lab.local 8.2-RELEASE FreeBSD 8.2-RELEASE #0: Tue Mar 15 09:14:03 UTC 2011 root@downloader1.lab.local:/usr/obj/usr/src/sys/GENERIC amd64 >Description: There is excessive duplicate ACKs and session freezes while downloading huge files at speed over http or ftp. tcpdump: 19:17:04.022367 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541894 ecr 783406220], length 0 19:17:04.022369 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541894 ecr 783406220], length 0 19:17:04.022553 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541894 ecr 783406220], length 0 19:17:04.022703 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541894 ecr 783406220], length 0 19:17:04.022707 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541894 ecr 783406220], length 0 19:17:04.022709 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541894 ecr 783406220], length 0 19:17:04.022856 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541894 ecr 783406220], length 0 19:17:04.023002 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541895 ecr 783406220], length 0 19:17:04.023005 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541895 ecr 783406220], length 0 19:17:04.023007 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541895 ecr 783406220], length 0 19:17:04.023151 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541895 ecr 783406220], length 0 19:17:04.023155 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541895 ecr 783406220], length 0 19:17:04.023157 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541895 ecr 783406220], length 0 19:17:04.023159 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541895 ecr 783406220], length 0 19:17:04.023200 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541895 ecr 783406220], length 0 19:17:04.023301 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541895 ecr 783406220], length 0 >How-To-Repeat: Setup two boxes, connect the via 1Gbit switch and run sequential wget or fetch tests. Receiving box generates excessive ACKs and in about 40% cases tcp session freezes and then timeouts. >Fix: Unknown, but looks like the was similar report http://lists.freebsd.org/pipermail/freebsd-net/2011-February/027895.html >Release-Note: >Audit-Trail: >Unformatted:
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