Re: [PATCH] kernel 2.4.19 & 2.5.38 - coredump sysctl

[Michael Sinz]

Bill Davidsen wrote:
> On Fri, 20 Sep 2002, Andrew Morton wrote:
> 
>>That seems a reasonable thing to want to do.
>>
>>>...
>>>The following format options are available in that string:
>>>
>>>       %P   The Process ID (current->pid)
>>>       %U   The UID of the process (current->uid)
>>>       %N   The command name of the process (current->comm)
>>>       %H   The nodename of the system (system_utsname.nodename)
>>>       %%   A "%"
>>>
>>>For example, in my clusters, I have an NFS R/W mount at /coredumps
>>>that all nodes have access to. The format string I use is:
>>>
>>>        sysctl -w "kernel.core_name_format=/coredumps/%H-%N-%P.core"
>>>
>>
>>Does it need to be this fancy?  Why not just have:
>>
>>        if (core_name_format is unset)
>>                use "core"
>>        else
>>                use core_name_format/nodename-uid-pid-comm.core
> 
> 
> Because this way you can do more things with where you put your dumps,
> such as using one element of this flexible method to select a directory,
> where the dump directories for various applications would be on a single
> NFS server, and dumps for another might be on another server, or all dumps
> of a certain kind could share a filename, where only the latest dump would
> be of interest (or take space).

Ahh, I never thought of using the program name for a directory.  That
would be nice as only those programs you pre-made a directory for would
dump (as the code does not create directories).  Using the UID for a
directory name works out to separate the dumps of different users.
(And works really well too - albeit on a non-Linux platform that happens
to have a simular feature.)

> The code seems to have very little overhead involved in the parse, and it
> gives a good deal of flexibility to the admin. I like the idea of a sysctl
> for setting the value, you don't want to have to reboot the system when an
> app goes sour and you need to save more than one dump to run it down, or
> need to mvoe the dump target dir somewhere with more space.
> 
> If you're worried about size make it a compile option, but if I (as an
> admin) need any control I really want a bunch of control I can set right
> now. I don't think most people will want this option, but it would be
> really useful in some cases.

I would be willing to do the work to make it configurable but when I
look at the size of the code, it really is not that large.  I tried
to keep it simple (KISS is always good).  I still need to write up the
documentation side of this into the patch too.  (I keep forgetting
to do that :-()

-- 
Michael Sinz -- Director, Systems Engineering -- Worldgate Communications
A master's secrets are only as good as
	the master's ability to explain them to others.