Home / server / Questions / 202041
In Process
redeye
Asked: 2010-11-16 07:46:02 +0800 CST

information about /proc/pid/sched

  • 772

Not sure this is the right place for this question, but here goes:

I'm trying to make some sense of the /proc/pid/sched and /proc/pid/task/tid/sched files for a highly threaded server process, however I was not able to find a good explanation of how to interpret this file ( just a few bits here: http://knol.google.com/k/linux-performance-tuning-and-measurement# ) . I assume this entry in procfs is related to newer versions of the kernel that run with the CFS scheduler?

CentOS distro running on a 2.6.24.7-149.el5rt kernel version with preempt rt patch.

Any thoughts?

linux scheduler

2 Answers

  1. You can find more documentation about the /proc/[pid]/sched file in this article:

    http://lwn.net/Articles/242900/

    Look at the comments. Most of the fields are explained.

    Addendum: the file is writeable to reset the statistics.

    • 3

  2. Probably "man proc" is the place to read! From the manual:

    /proc/[pid]/task
    (since Linux 2.6.0-test6) This is a directory that contains one subdirectory for each thread in the process. The name of each subdirectory is the numerical thread ID ([tid]) of the thread (see gettid(2)). Within each of these subdirectories, there is a set of files with the same names and contents as under the /proc/[pid] directories. For attributes that are shared by all threads, the contents for each of the files under the task/[tid] subdirectories will be the same as in the corresponding file in the parent /proc/[pid] directory (e.g., in a multithreaded process, all of the task/[tid]/cwd files will have the same value as the /proc/[pid]/cwd file in the parent directory, since all of the threads in a process share a working directory). For attributes that are distinct for each thread, the corresponding files under task/[tid] may have different values (e.g., various fields in each of the task/[tid]/status files may be different for each thread).

    In a multithreaded process, the contents of the /proc/[pid]/task directory are not available if the main thread has already terminated (typically by calling pthread_exit(3)).

    So, basically understanding /proc/pid/task/ means understanding proc itself.

    • -3