Bug 192298
| Summary: | net/dhcprelya consumes cpu on FreeBSD 10 | ||||||
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| Product: | Ports & Packages | Reporter: | Adam McDougall <ebay> | ||||
| Component: | Individual Port(s) | Assignee: | Sergey Matveychuk <sem> | ||||
| Status: | Closed FIXED | ||||||
| Severity: | Affects Only Me | CC: | lenzi.sergio | ||||
| Priority: | --- | ||||||
| Version: | Latest | ||||||
| Hardware: | Any | ||||||
| OS: | Any | ||||||
| Attachments: |
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over to maintainer. (In reply to mcdouga9 from comment #0) But what about real packet rate for DHCP packets? This is with zero DHCP requests because I can reproduce the issue with no active network connections (cables unplugged). So far I can reproduce it on systems with 'em' nic, 82574L and 82546EB but I could not reproduce it in Xen with xn0 or re0. I verified there is no problem in 9. Created attachment 151043 [details]
increase timeout from 10 usec to 1ms
increase the select timeout from 10usec to 1000 usec
this will reduce the number of system calls in the select loop by 1/100
so the program does not consumes cpu on idle any more
It worked for me...
put the attach in the file directory of the port, with a name patch-xxxx and rebuild + reinstall the port.. Thank you for the patch, it greatly reduces the CPU load but does not completely eliminate it on an idle network: PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND 1295 root 2 20 0 23212K 2704K bpf 0 0:01 0.29% dhcprelya I'll use the patch for now but I think the bug report should stay open for a fuller fix. |
I've been using dhcprelya for a while because it worked well with tun0 and openvpn. After upgrading such a server to FreeBSD 10, I noticed the load average stays around 0.70, approx 15% cpu usage from dhcprelya, and it is making repetitive calls. systat -vmstat 1 shows 10-30 thousand interrupts per second on the cpu timer with kern.eventtimer.timer=LAPIC (default), or 2 thousand per second with i8254 (lower cpu usage, but same load average). This issue can be reproduced easily, I just install dhcprelya on 10 and enable it on a spare interface with a dummy IP (no link necessary). I am willing to help figure this out if I can get some help. Thanks. rc.conf: dhcprelya_enable="YES" dhcprelya_servers="192.168.0.10" dhcprelya_ifaces="em3" truss -p shows: select(7,{6},0x0,0x0,{0.000010 }) = 0 (0x0) select(7,{6},0x0,0x0,{0.000010 }) = 0 (0x0) select(7,{6},0x0,0x0,{0.000010 }) = 0 (0x0) select(7,{6},0x0,0x0,{0.000010 }) = 0 (0x0) ... (many) select(7,{6},0x0,0x0,{0.000010 }) = 0 (0x0) select(7,{6},0x0,0x0,{0.000010 }) = 0 (0x0) read(5,0x80185b000,524288) = 0 (0x0) select(7,{6},0x0,0x0,{0.000010 }) = 0 (0x0) select(7,{6},0x0,0x0,{0.000010 }) = 0 (0x0) select(7,{6},0x0,0x0,{0.000010 }) = 0 (0x0) nanosleep({0.001000000 }) = 0 (0x0) select(7,{6},0x0,0x0,{0.000010 }) = 0 (0x0) ... kdump says: 1086 dhcprelya RET select 0 1086 dhcprelya CALL select(0x7,0x7fffffffe9e0,0,0,0x7fffffffea90) 1086 dhcprelya RET select 0 1086 dhcprelya CALL select(0x7,0x7fffffffe9e0,0,0,0x7fffffffea90) 1086 dhcprelya RET select 0 1086 dhcprelya CALL select(0x7,0x7fffffffe9e0,0,0,0x7fffffffea90) ... procstat -k 1086 flips between: PID TID COMM TDNAME KSTACK 1086 100395 dhcprelya - <running> 1086 100396 dhcprelya - mi_switch sleepq_catch_signals sleepq_timedwait_sig _sleep bpfread devfs_read_f dofileread kern_readv sys_read amd64_syscall Xfast_syscall and PID TID COMM TDNAME KSTACK 1086 100395 dhcprelya - mi_switch sleepq_catch_signals sleepq_timedwait_sig _cv_timedwait_sig_sbt seltdwait kern_select sys_select amd64_syscall Xfast_syscall 1086 100396 dhcprelya - mi_switch sleepq_catch_signals sleepq_timedwait_sig _sleep bpfread devfs_read_f dofileread kern_readv sys_read amd64_syscall Xfast_syscall