I was running a stock 7.2b4 Postgres with pgbench.
RedHat Linux 7.2, stock everything.
Dual PIII 650MHZ
SMP kernel
1G RAM
EXT3 file system
Adaptec SCSI disks, one for /base and ont for/pg_xlog
pgbench scaled to 50
./pgbench -n -t 100 -h $HOST -c 100 bench
It hung in the checkpoint. I wasn't able to trace it.