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2answers
51 views

Where is a named semaphore stored? [closed]

A named semaphore (using semaphore.h) is identified by a name in the form /somename; that is, a null-terminated string of up to NAME_MAX-4 (i.e., 251) characters consisting of an initial slash, ...
5
votes
1answer
78 views

Performing atomic write operations in a file in bash

After going through the bash documentation, this question and this one it's still not clear to me how can I perform atomic write (append) operations to a file in bash. I have a script that is run in ...
0
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0answers
123 views

scripts/checkpatch.pl: Warning: consider using a completion

I'm currently writing a kernel driver that involves moving large amounts data from userspace to or from a peripheral, via a ring of bounce buffers. The buffer completion callback ups a semaphore, and ...
2
votes
0answers
69 views

process waiting for a semaphore

If I have a process that is in sleep state and i can see in ps' column WCHAN that is waiting to obtain a semaphore, is there any way to find the adress of that semaphore?
1
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0answers
358 views

How to debug a semop failure?

Using a 2.6.30-gentoo-r4 Linux a very complex system of php code is executed (with 4.4.9-pl0-gentoo and 5.2.10-pl0-gentoo), which occasionally runs into a semaphore blocking problem. The call to the ...
10
votes
1answer
25k views

How to get proccesses currently running semaphores by /proc?

I wonder how to get processes currently running semaphores by /proc ? I guess it's possible by SysVIPC subdirectory.But I don't know how to use this commands. Ubuntu 12.10
4
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1answer
12k views

How do I increase the number of semaphore arrays in Linux?

In a Debian lenny server running postgresql, I noticed that a lack of semaphore arrays is preventing Apache from starting up. Looking at the limits, I see 128 arrays used out of 128 arrays maximum, ...
11
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3answers
22k views

what is the difference between spin locks and semaphores?

What are the basic differences between spin locks and semaphores in action?
3
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3answers
10k views

Why are spin locks good choices in Linux Kernel Design instead of something more common in userland code, such as semaphore or mutex?

I understand that Spinlocks are real waste in Linux Kernel Design. I would like to know why is it like spin locks are good choices in Linux Kernel Design instead of something more common in userland ...
28
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7answers
11k views

What Unix commands can be used as a semaphore/lock?

I want to run multiple Bash shell scripts in parallel. However, I want to avoid race conditions. What Unix commands are truly atomic that I could use for this purpose, and how can I use them?