| Title: | DIGITAL UNIX (FORMERLY KNOWN AS DEC OSF/1) |
| Notice: | Welcome to the Digital UNIX Conference |
| Moderator: | SMURF::DENHAM |
| Created: | Thu Mar 16 1995 |
| Last Modified: | Fri Jun 06 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 10068 |
| Total number of notes: | 35879 |
When I do a "ps auxw", a few processes have a state of 'U', which according to the man page is a "Uninterruptible sleeping process." How can a process get into this state? In this particular case, the process is switching between U,S, and R states (and process is running much slower than normal); however, I have seen some processes get into this U state, never come out and couldn't be killed by user or superuser. TIA, Keith Austin PS. O/S is DU V3.2G [Posted by WWW Notes gateway]
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 8700.1 | Some info | RHETT::PARKER | Thu Feb 06 1997 11:51 | 17 | |
Hi Keith,
When a process blocks waiting for I/O in a device driver, the
driver often uses sleep/wakeup as a synchronization mechanism.
In the call to sleep/mpsleep, one specifies if the sleep can
be interrupted by OR'ing in a flag called PCATCH. If this is
not OR'ed in, the sleep cannot be interrupted by a signal. The
signal will get OR'ed into the mask for later delivery.
What do the processes you are interested in do? Could be the
disk/tape driver or pseudo-tty driver or who knows...
Hth,
Lee
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| 8700.2 | SMURF::DENHAM | Digital UNIX Kernel | Thu Feb 06 1997 13:24 | 3 | |
For these kinds of issues, kernel stack traces of the stuck
processes is most helpful. Also knowing who's the parent process
can help.
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