Messages in this thread | | | Date | Thu, 4 Feb 1999 22:32:08 -0800 (PST) | From | Truxton Fulton <> | Subject | processes freezing between v2.1.130 and v2.2.1 |
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Dear Linus et al,
There is a kernel peculiarity introduced after v2.1.130. I have been seeing it happen with all the 2.2.0-pre releases, but it is intermittent enough to make it hard to reproduce. What happens is that a process will block for a long time. This happens with xload, xclock, netscape, and other apps too. I have two machines with identical filesystems. This problem does not happen on my 96MB pentium with local disks, rather it happens on my 24MB i486 with all filesystems nfs mounted (although it has a local swap disk). High load average and swapping seem to trigger this bug. A process will just get stuck for a long while. Using strace on xload and xclock reveals a select() waiting on fd 3 for hundreds or sometimes thousands of seconds. I remember someone else on the mailing list puzzling at netscape doing a similar select(). I can believe netscape has enough bugs of its own to cause this bad behaviour, but what I find strange is that other relatively simple programs like xload are doing the same thing, and that reverting to linux v2.1.130 seems to cure the problem. v2.2.1 contained some promising sounding comments in the mm code about fixing a scheduling problem, but v2.2.1 alas still has the same problem. If I can assist in debugging this further, I will be glad to.
-Truxton
vaiva@endorphin(/tmp)>uname -a Linux endorphin.truxton.com 2.2.1 #1 Sun Jan 31 15:37:49 PST 1999 i486 unknown vaiva@endorphin(/tmp)>free -t total used free shared buffers cached Mem: 22628 22108 520 9908 4 8984 -/+ buffers/cache: 13120 9508 Swap: 83284 40756 42528 Total: 105912 62864 43048
[root@endorphin /root]# ps waux | egrep "xload|PID" USER PID %CPU %MEM SIZE RSS TTY STAT START TIME COMMAND root 1430 0.0 1.7 1132 400 p5 S 21:31 0:00 egrep xload |PID vaiva 319 0.0 1.3 2464 308 1 S 23:03 0:03 xload -fn 6x10 -hl lightblue -geometry 250x50-106+0 -scale 2 -update 8 [root@endorphin /root]# strace -p 319 select(4, [3], [], [], {493, 860000} <unfinished ...> [root@endorphin /root]# [root@endorphin /root]# ps waux | egrep "xclock|PID" USER PID %CPU %MEM SIZE RSS TTY STAT START TIME COMMAND root 1436 0.0 1.7 1132 400 p5 S 21:32 0:00 egrep xclock |PID vaiva 324 0.0 1.4 2412 332 1 S 23:03 0:01 xclock -fn 6x13 -geometry 100x100-0+0 -update 1 [root@endorphin /root]# strace -p 324 select(4, [3], [], [], {521, 30000} <unfinished ...> [root@endorphin /root]# strace -p 324 select(4, [3], [], [], {504, 10000} <unfinished ...> [root@endorphin /root]# strace -p 324 select(4, [3], [], [], {493, 800000} <unfinished ...> [root@endorphin /root]# strace -p 324 select(4, [3], [], [], {479, 50000} <unfinished ...>
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