Re: merging regtests

[David Kastrup]

Reinhold Kainhofer <address@hidden> writes:

> Am Montag, 5. September 2011, 23:09:14 schrieb Janek Warchoł:
>> May i ask for a very short explanation of what was wrong?  Were there
>> too many regtest files in the directory and this made it impossible to
>> compile them, and therefore check them?
>
> The makefile in input/regression/ collects all regtests in the variable 
> COLLATED_FILES. For an out-of-source build, each regtest will have the 
> absolute path, which for a gub build was >130 characters for the source 
> directory. 
>
> Now the problem is that we have >1000 regtests, each of which has an absolute 
> path >131 chars. As a consequence the list in COLLATED_FILES had more than 
> 131000 characters, which was then passed to the lys-to-tely script on the 
> command line. 
> On the other hand, the Linux kernel allows the command line to have a maximum 
> length of a little more than 131000 characters...

man execve

   Limits on size of arguments and environment
       Most  Unix  implementations  impose some limit on the total size of the
       command-line argument (argv) and environment (envp) strings that may be
       passed to a new program.  POSIX.1 allows an implementation to advertise
       this limit using the ARG_MAX constant (either defined in <limits.h>  or
       available at run time using the call sysconf(_SC_ARG_MAX)).

       On  Linux prior to kernel 2.6.23, the memory used to store the environ‐
       ment and argument strings was limited to 32 pages (defined by the  ker‐
       nel  constant  MAX_ARG_PAGES).  On architectures with a 4-kB page size,
       this yields a maximum size of 128 kB.

       On kernel 2.6.23 and later, most architectures  support  a  size  limit
       derived  from  the  soft RLIMIT_STACK resource limit (see getrlimit(2))
       that is in force at the time of the execve() call.  (Architectures with
       no  memory  management  unit are excepted: they maintain the limit that
       was in effect before kernel 2.6.23.)  This change  allows  programs  to
       have  a much larger argument and/or environment list.  For these archi‐
       tectures, the total size is limited to 1/4 of the allowed  stack  size.

So using a recent enough kernel should get rid of that annoyance.

-- 
David Kastrup