iotop complains "CONFIG_TASK_DELAY_ACCT not enabled in kernel" only for specific process

I'm trying to use iotop to determine whether the CPUs are waiting on I/O at any point for a specific program called bwa (it's a next-generation sequence alignment program). If I start iotop without specifying a specific process (-p pid), I get all of the expected information, including SWAPIN and IO>, but the process I'm interested in doesn't show up on the list. If I then specify the process I'm interested in, iotop complains that "CONFIG_TASK_DELAY_ACCT not enabled in kernel". For sanity, I verified in my kernel config file (/boot/config-3.7.10-1.11-desktop) that CONFIG_TASK_DELAY_ACCT is enabled (CONFIG_TASK_DELAY_ACCT=y).

The questions:

1. What could make iotop think CONFIG_TASK_DELAY_ACCT is not enabled for a specific process when I know it is?
2. Can I fix it?
3. Have I overlooked something silly?

Solution 1:

Brock's Blog describes how you can do that with Ubuntu:

1. Edit /etc/default/grub, adding “delayacct” as an option to the GRUB_CMDLINE_LINUX_DEFAULT entry. If you hadn’t already modified that line, it would go from

   GRUB_CMDLINE_LINUX_DEFAULT=""
   

   to

   GRUB_CMDLINE_LINUX_DEFAULT="delayacct"
   

2. Run “sudo update-grub”

3. Reboot, and you should be good to go