Hi Peter, On 04/01/2013 08:40 PM, Peter Hurley wrote: > On Mon, 2013-04-01 at 19:27 +0530, Vineet Gupta wrote: >> Hi, >> >> Any thoughts: I observe the same issue even with CONFIG_PREEMPT and >> CONFIG_PREEMPT_COUNT >> >> -Vineet >> >> On 03/30/2013 06:05 PM, Vineet Gupta wrote: >>> Hi, >>> >>> I've been stress testing ARC Linux 3.8 (same happens for 3.9-rc3 as well). The >>> setup has 3 telnet sessions, each running find . -name "*" in a loop. >>> The platform is a FPGA @ 80 MHz, running a single core ARC700 so kernel .config >>> has !SMP and PREEMPT_NONE. >>> >>> After ~10 mins of run, I see that one of the telnet session gets stuck (and later >>> the 2nd one as well), while system is still alive, 3rd telnet is running find merrily. >>> >>> [ARCLinux]$ ps >>> .... >>> 7 root 0:00 inetd >>> 62 root 0:00 -/bin/sh >>> 64 root 1:34 telnetd -i -l /bin/sh >>> 65 root 0:00 /bin/sh >>> 75 root 1:47 telnetd -i -l /bin/sh >>> 76 root 0:00 /bin/sh >>> 79 root 0:53 telnetd -i -l /bin/sh >>> 80 root 0:00 /bin/sh >>> 281 root 0:00 find / -name * <--- stuck >>> 358 root 0:03 find / -name * <--- stuck >>> 377 root 0:00 find / -name * >>> 378 root 0:00 ps >>> >>> Hung find task is sitting in the schedule() call in n_tty_write() >>> >>> [ARCLinux]$ cat /proc/281/stack >>> [<8065945e>] n_tty_write+0x23a/0x424 >>> [<80655cd4>] tty_write+0x1ac/0x2d4 >>> [<805976ba>] vfs_write+0x92/0x110 >>> [<80597816>] sys_write+0x4e/0x88 >>> [<8050e780>] ret_from_system_call+0x0/0x4 > Likely the writer is stuck because the receive buffer is full and the > reader is hung. What are the respective shells and telnetd doing? telnetd is in select syscall - waiting for new connections ? shell is wait(2)ing - likely on the child "find" task. / # cat /proc/62/stack [<8059e26a>] do_select+0x4b6/0x59c [<8059e4f8>] core_sys_select+0x1a8/0x690 [<8059ea74>] sys_pselect6+0x94/0x254 [<80505fb4>] ret_from_system_call+0x0/0x4 / # cat /proc/63/stack [<80513a4a>] do_wait+0x166/0x188 [<80513ace>] sys_wait4+0x62/0xac [<80505fb4>] ret_from_system_call+0x0/0x4 / # cat /proc/445/stack [<8064c7f2>] n_tty_write+0x23a/0x424 [<80649038>] tty_write+0x1a0/0x2b4 [<8058a4b6>] vfs_write+0x92/0x110 [<8058a612>] sys_write+0x4e/0x88 [<80505fb4>] ret_from_system_call+0x0/0x4 > PS - include the controlling tty column in your ps output :) S UID PID PPID VSZ RSS TTY STIME TIME CMD S 0 62 47 1768 488 0:0 16:01 00:01:44 telnetd -i -l /bin/sh S 0 63 62 1768 512 pts2 16:01 00:00:00 /bin/sh S 0 445 63 1840 488 pts2 16:30 00:00:00 find / -name * Thx, -Vineet -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
