makedumpfile 1.5.0 takes much more time to dump

[Vivek Goyal]

Hi Atsushi san,

We tried makedumpfile 1.5.0 on a 1TB machine and it seems to regress
badly. We reserved 192MB of memory and following are test results.

#1. makedumpfile-1.4.2 -E --message-level 1 -d 31
real     3m47.520s
user     0m56.543s
sys	 2m41.631s

#2. makedumpfile-1.5.0 -E --message-level 1 -d 31
real     52m25.262s
user     32m51.310s
sys	 18m53.265s

#3. makedumpfile-1.4.2 -c --message-level 1 -d 31
real     8m49.107s
user     4m34.180s
sys	 4m8.691s

#4. makedumpfile-1.5.0 -c --message-level 1 -d 31
real     46m48.985s
user     29m35.203s
sys	 16m43.149s

Thanks
Vivek