Date: Sun, 25 Sep 2016 21:58:15 +0300 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: Julien Charbon <jch@freebsd.org> Cc: Konstantin Belousov <kostikbel@gmail.com>, freebsd-stable@FreeBSD.org, hiren panchasara <hiren@strugglingcoder.info> Subject: Re: 11.0 stuck on high network load Message-ID: <20160925185815.GA6177@zxy.spb.ru> In-Reply-To: <20160923191656.GF2840@zxy.spb.ru> References: <20160919204328.GN2840@zxy.spb.ru> <8ba75d6e-4f01-895e-0aed-53c6c6692cb9@freebsd.org> <20160920202633.GQ2840@zxy.spb.ru> <f644cd52-4377-aa90-123a-3a2887972bbc@freebsd.org> <20160921195155.GW2840@zxy.spb.ru> <e4e0188c-b22b-29af-ed15-b650c3ec4553@gmail.com> <20160922095331.GB2840@zxy.spb.ru> <67862b33-63c0-2f23-d254-5ddc55dbb554@freebsd.org> <20160922102045.GC2840@zxy.spb.ru> <20160923191656.GF2840@zxy.spb.ru>
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On Fri, Sep 23, 2016 at 10:16:56PM +0300, Slawa Olhovchenkov wrote: > On Thu, Sep 22, 2016 at 01:20:45PM +0300, Slawa Olhovchenkov wrote: > > > On Thu, Sep 22, 2016 at 12:04:40PM +0200, Julien Charbon wrote: > > > > > >> These paths can indeed compete for the same INP lock, as both > > > >> tcp_tw_2msl_scan() calls always start with the first inp found in > > > >> twq_2msl list. But in both cases, this first inp should be quickly used > > > >> and its lock released anyway, thus that could explain your situation it > > > >> that the TCP stack is doing that all the time, for example: > > > >> > > > >> - Let say that you are running out completely and constantly of tcptw, > > > >> and then all connections transitioning to TIME_WAIT state are competing > > > >> with the TIME_WAIT timeout scan that tries to free all the expired > > > >> tcptw. If the stack is doing that all the time, it can appear like > > > >> "live" locked. > > > >> > > > >> This is just an hypothesis and as usual might be a red herring. > > > >> Anyway, could you run: > > > >> > > > >> $ vmstat -z | head -2; vmstat -z | grep -E 'tcp|sock' > > > > > > > > ITEM SIZE LIMIT USED FREE REQ FAIL SLEEP > > > > > > > > socket: 864, 4192664, 18604, 25348,49276158, 0, 0 > > > > tcp_inpcb: 464, 4192664, 34226, 18702,49250593, 0, 0 > > > > tcpcb: 1040, 4192665, 18424, 18953,49250593, 0, 0 > > > > tcptw: 88, 16425, 15802, 623,14526919, 8, 0 > > > > tcpreass: 40, 32800, 15, 2285, 632381, 0, 0 > > > > > > > > In normal case tcptw is about 16425/600/900 > > > > > > > > And after `sysctl -a | grep tcp` system stuck on serial console and I am reset it. > > > > > > > >> Ideally, once when everything is ok, and once when you have the issue > > > >> to see the differences (if any). > > > >> > > > >> If it appears your are quite low in tcptw, and if you have enough > > > >> memory, could you try increase the tcptw limit using sysctl > > > > > > > > I think this is not eliminate stuck, just may do it less frequency > > > > > > You are right, it would just be a big hint that the tcp_tw_2msl_scan() > > > contention hypothesis is the right one. As I see you have plenty of > > > memory on your server, thus could you try with: > > > > > > net.inet.tcp.maxtcptw=4192665 > > > > > > And see what happen. Just to validate this hypothesis. > > > > This is bad way for validate, with maxtcptw=16384 happened is random > > and can be waited for month. After maxtcptw=4192665 I am don't know > > how long need to wait for verification this hypothesis. > > > > More frequency (may be 3-5 times per day) happening less traffic drops > > (not to zero for minutes). May be this caused also by contention in > > tcp_tw_2msl_scan, but fast resolved (stochastic process). By eating > > CPU power nginx can't service connection and clients closed > > connections and need more TIME_WAIT and can trigered > > tcp_tw_2msl_scan(reuse=1). After this we can got live lock. > > > > May be after I learning to catch and dignostic this validation is more > > accurately. > > Some more bits: > > socket: 864, 4192664, 30806, 790,28524160, 0, 0 > ipq: 56, 32802, 0, 1278, 1022, 0, 0 > udp_inpcb: 464, 4192664, 44, 364, 14066, 0, 0 > udpcb: 32, 4192750, 44, 3081, 14066, 0, 0 > tcp_inpcb: 464, 4192664, 38558, 378,28476709, 0, 0 > tcpcb: 1040, 4192665, 30690, 738,28476709, 0, 0 > tcptw: 88, 32805, 7868, 772, 8412249, 0, 0 > > last pid: 49575; load averages: 2.00, 2.05, 3.75 up 1+01:12:08 22:13:42 > 853 processes: 15 running, 769 sleeping, 35 waiting, 34 lock > CPU 0: 0.0% user, 0.0% nice, 0.0% system, 100% interrupt, 0.0% idle > CPU 1: 0.0% user, 0.0% nice, 0.0% system, 0.0% interrupt, 100% idle > CPU 2: 0.0% user, 0.0% nice, 0.0% system, 0.0% interrupt, 100% idle > CPU 3: 0.0% user, 0.0% nice, 0.0% system, 0.0% interrupt, 100% idle > CPU 4: 0.0% user, 0.0% nice, 0.0% system, 0.0% interrupt, 100% idle > CPU 5: 0.0% user, 0.0% nice, 0.0% system, 0.0% interrupt, 100% idle > CPU 6: 0.0% user, 0.0% nice, 0.4% system, 0.0% interrupt, 99.6% idle > CPU 7: 0.0% user, 0.0% nice, 0.0% system, 0.0% interrupt, 100% idle > CPU 8: 0.0% user, 0.0% nice, 0.0% system, 0.0% interrupt, 100% idle > CPU 9: 0.0% user, 0.0% nice, 0.0% system, 0.0% interrupt, 100% idle > CPU 10: 0.0% user, 0.0% nice, 0.4% system, 0.0% interrupt, 99.6% idle > CPU 11: 0.0% user, 0.0% nice, 0.0% system, 0.0% interrupt, 100% idle > Mem: 8659M Active, 8385M Inact, 107G Wired, 1325M Free > ARC: 99G Total, 88G MFU, 10G MRU, 32K Anon, 167M Header, 529M Other > Swap: 32G Total, 32G Free I can collect some more info. First: 1046 - - R 125:10.79 nginx: worker process (nginx) 1047 kqread - I 150:11.98 nginx: worker process (nginx) 1049 kqread - I 145:58.35 nginx: worker process (nginx) 1050 kqread - I 136:33.36 nginx: worker process (nginx) 1051 kqread - I 140:59.73 nginx: worker process (nginx) 1052 kqread - I 137:18.12 nginx: worker process (nginx) pid 1046 is nginx running on CPU0 (affinity mask set). # procstat -k -k 1046 PID TID COMM TDNAME KSTACK 1046 100686 nginx - mi_switch+0xd2 critical_exit+0x7e lapic_handle_timer+0xb1 Xtimerint+0x8c __mtx_lock_sleep+0x168 zone_fetch_slab+0x47 zone_import+0x52 zone_alloc_item+0x36 keg_alloc_slab+0x63 keg_fetch_slab+0x16e zone_fetch_slab+0x6e zone_import+0x52 uma_zalloc_arg+0x36e m_getm2+0x14f m_uiotombuf+0x64 sosend_generic+0x356 soo_write+0x42 dofilewrite+0x87 Tracing command nginx pid 1046 tid 100686 td 0xfffff8014485f500 sched_switch() at 0xffffffff804c956d = sched_switch+0x6ad/frame 0xfffffe20216992a0 /usr/src/sys/kern/sched_ule.c:1973 mi_switch() at 0xffffffff804a8d92 = mi_switch+0xd2/frame 0xfffffe20216992d0 /usr/src/sys/kern/kern_synch.c:465 critical_exit() at 0xffffffff804a6bee = critical_exit+0x7e/frame 0xfffffe20216992f0 /usr/src/sys/kern/kern_switch.c:219 lapic_handle_timer() at 0xffffffff80771701 = lapic_handle_timer+0xb1/frame 0xfffffe2021699330 /usr/src/sys/x86/x86/local_apic.c:1185 Xtimerint() at 0xffffffff806cbbcc = Xtimerint+0x8c/frame 0xfffffe2021699330 /usr/src/sys/amd64/amd64/apic_vector.S:135 --- interrupt, rip = 0xffffffff804de424, rsp = 0xfffffe2021699400, rbp = 0xfffffe2021699420 --- lock_delay() at 0xffffffff804de424 = lock_delay+0x54/frame 0xfffffe2021699420 /usr/src/sys/kern/subr_lock.c:127 __mtx_lock_sleep() at 0xffffffff80484dc8 = __mtx_lock_sleep+0x168/frame 0xfffffe20216994a0 /usr/src/sys/kern/kern_mutex.c:512 zone_fetch_slab() at 0xffffffff806a4257 = zone_fetch_slab+0x47/frame 0xfffffe20216994e0 /usr/src/sys/vm/uma_core.c:2378 zone_import() at 0xffffffff806a4312 = zone_import+0x52/frame 0xfffffe2021699530 /usr/src/sys/vm/uma_core.c:2501 zone_alloc_item() at 0xffffffff806a0986 = zone_alloc_item+0x36/frame 0xfffffe2021699570 /usr/src/sys/vm/uma_core.c:2591 keg_alloc_slab() at 0xffffffff806a2463 = keg_alloc_slab+0x63/frame 0xfffffe20216995d0 /usr/src/sys/vm/uma_core.c:965 keg_fetch_slab() at 0xffffffff806a48ce = keg_fetch_slab+0x16e/frame 0xfffffe2021699620 /usr/src/sys/vm/uma_core.c:2349 zone_fetch_slab() at 0xffffffff806a427e = zone_fetch_slab+0x6e/frame 0xfffffe2021699660 /usr/src/sys/vm/uma_core.c:2375 zone_import() at 0xffffffff806a4312 = zone_import+0x52/frame 0xfffffe20216996b0 /usr/src/sys/vm/uma_core.c:2501 uma_zalloc_arg() at 0xffffffff806a147e = uma_zalloc_arg+0x36e/frame 0xfffffe2021699720 /usr/src/sys/vm/uma_core.c:2531 m_getm2() at 0xffffffff8048231f = m_getm2+0x14f/frame 0xfffffe2021699790 /usr/src/sys/kern/kern_mbuf.c:830 m_uiotombuf() at 0xffffffff80516044 = m_uiotombuf+0x64/frame 0xfffffe20216997e0 /usr/src/sys/kern/uipc_mbuf.c:1535 sosend_generic() at 0xffffffff8051ce56 = sosend_generic+0x356/frame 0xfffffe20216998a0 soo_write() at 0xffffffff804fd872 = soo_write+0x42/frame 0xfffffe20216998d0 dofilewrite() at 0xffffffff804f5c97 = dofilewrite+0x87/frame 0xfffffe2021699920 kern_writev() at 0xffffffff804f5978 = kern_writev+0x68/frame 0xfffffe2021699970 sys_writev() at 0xffffffff804f5be6 = sys_writev+0x36/frame 0xfffffe20216999a0 amd64_syscall() at 0xffffffff806e4051 = amd64_syscall+0x2c1/frame 0xfffffe2021699ab0 Xfast_syscall() at 0xffffffff806cb2bb = Xfast_syscall+0xfb/frame 0xfffffe2021699ab0 --- syscall (121, FreeBSD ELF64, sys_writev), rip = 0x8019cc6ba, rsp = 0x7fffffffd688, rbp = 0x7fffffffd6c0 --- And I am now collect and save kernel dump. # vmstat -M /var/crash/vmcore.1 -z| grep -i mbuf mbuf_packet: 256, 52276395, 26987, 189713,705271653, 0, 0 mbuf: 256, 52276395, 61994, 782439,46250344524, 0, 0 mbuf_cluster: 2048, 1048576, 49207, 34461, 293307, 0, 0 mbuf_jumbo_page: 4096, 4084093, 61839, 613537,8265099417, 0, 0 mbuf_jumbo_9k: 9216, 3630303, 0, 0, 0, 0, 0 mbuf_jumbo_16k: 16384, 2722728, 0, 0, 0, 0, 0
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