kern/120749: Suggest upping the default kern.ps_arg_cache_limit

peter.schuller at peter.schuller at
Sun Feb 17 09:10:03 UTC 2008

>Number:         120749
>Category:       kern
>Synopsis:       Suggest upping the default kern.ps_arg_cache_limit
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Sun Feb 17 09:10:02 UTC 2008
>Originator:     peter.schuller at
>Release:        FreeBSD 6.2-RELEASE-p8 i386
System: FreeBSD 6.2-RELEASE-p8 FreeBSD 6.2-RELEASE-p8 #0: Fri Oct 19 05:50:09 CEST 2007 scode at i386

   I would like to suggest that the default value of kern.ps_arg_cache_limit be significantly
   increased. Right now, it is set to PAGE_SIZE / 16, which is 256 on typical machines.

   I do not know enough to determine whether there is a technical reason for wanting it
   this low other than just pure memory consumption, but from the perspective of a user
   on an even remotely modern system a limit of 256 characters is not very useful. The
   amount of overhead per process is so small relative to the likely size of the process
   that the annoyance of 256 has to overweigh it for me (even if the memory is wired).
   I happen to know to change this variable, but the default behavior is sure to be
   confusing to new users (expecting ps auxwww | grep XXX to work). Several real-life
   non-extreme command lines are longer in this day and age (and this was true already
   several years ago). If someone is running FreeBSD under extremely memory constrictive
   conditions (relative to the amount of processes), that, to me, seems sufficiently
   exotic that tweaking of the system is necessary.
   In short, in an attempt to cater to normal use and the principle of least surprise,
   I suggest upping the default value to at least 1024 bytes.

   Change kern/kern_exec.c. Presumably changing it is less work than applying a patch,
   so I am not including one.


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