Messages in this thread | | | Date | Mon, 24 Sep 2007 09:54:17 +0200 | From | "Johan Walles" <> | Subject | "cat /proc/20502/wchan" vs strace vs man page |
| |
Try this: 1. At one prompt, do "cat". Now, switch to another prompt and... 2. Do "pstree -p|grep cat" to find out the PID of your cat command. I get 20502. 3. Do "cat /proc/20502/wchan". I get "0" here. 4. Do "strace -p 20502". I get "read(0, <unfinished ...>" here.
So wchan says cat is waiting for "0". Strace says cat is waiting for read (which sounds much more probable to me).
Is "0" the correct contents of /proc/20502/wchan? I expected it to say something about "read".
According to "man proc", wchan "is the "channel" in which the process is waiting. It is the address of a system call". "0" doesn't seem to fit that description. Is "0" or the man page wrong?
I'm on Ubuntu 7.04 Feisty, i686, have manpages "2.39-1", kernel "Linux version 2.6.20-16-generic (root@terranova) (gcc version 4.1.2 (Ubuntu 4.1.2-0ubuntu4)) #2 SMP Fri Aug 31 00:55:27 UTC 2007".
I'm not subscribed to the list, please CC me on replies.
Cheers //Johan - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |