mxqsub: Set default tmpdir size to 10 GiB

Commit efe43f4 ("mxqsub: Default tmpdir to 100G") made --tmpdir=100
the default.

The 100G number was, of course, arbitrary, and seems to be a bit on the
high side. Experience shows that the free disk space now is often the
limiting factor which prevents servers from taking additional jobs.

for h in $(hostconfig --list mxqd); do
  ssh $h  'd=$(($(stat -f -c%b /scratch/local2)*4/1024/1024));c=$(nproc); echo $d GB / $c cores= $(($d/$c)) $(hostname)'
done | sort -k6n

385 GB 64 cores = 6 simsalabimbambasaladusaladim.molgen.mpg.de
465 GB 64 cores = 7 esodophobie.molgen.mpg.de
915 GB 80 cores = 11 acedia.molgen.mpg.de
915 GB 80 cores = 11 avaritia.molgen.mpg.de
915 GB 80 cores = 11 fordprefect.molgen.mpg.de
[...]
7449 GB 64 cores = 116 peanutbutterjellytime.molgen.mpg.de
14901 GB 64 cores = 232 crunchyfrog.molgen.mpg.de
14901 GB 64 cores = 232 dirtyfork.molgen.mpg.de
29804 GB 128 cores = 232 kronos.molgen.mpg.de

Set the limit to 10G.

mxqsub.c

@@ -67,7 +67,7 @@ static void print_usage(void)
     "\n"
     "  -j, --processors=NUMBER  set number of processors    (default: 1)\n"
     "  -m, --memory=SIZE        set amount of memory        (default: 2G)\n"
-    "  --tmpdir=SIZE            set size of MXQ_JOB_TMPDIR  (default: 100G)\n"
+    "  --tmpdir=SIZE            set size of MXQ_JOB_TMPDIR  (default: 10G)\n"
     "  --gpu                    request a gpu\n"
     "  --blacklist=STRING       set list of blacklisted servers (default: '')\n"
     "  --whitelist=STRING       set list of whitelisted servers (default: '')\n"
@@ -803,7 +803,7 @@ int main(int argc, char *argv[])
     arg_debug          = 0;
     arg_jobflags       = 0;
     arg_groupid        = UINT64_UNSET;
-    arg_tmpdir         = 100;      // 100G
+    arg_tmpdir         = 10;       // 10G
     arg_blacklist      = NULL;
     arg_whitelist      = NULL;
     arg_prerequisites  = "";