I was trying to use iotop yesterday on my workstation and it was complaining that “CONFIG_TASK_DELAY_ACCT” was not enabled in the kernel. “OK,” I thought, “I can rebuild the kernel, no problem.” So I went to rebuild the kernel and discovered that CONFIG_TASK_DELAY_ACCT was already enabled along with the associated config options needed for iotop, so I was confused.

After a little spelunking of old mailing list entries (which I am trying to spare you with this post, dear reader), I discovered that the Ubuntu folks flipped around how the “nodelayacct” kernel boot parameter works for various arcane reasons. Here’s the short version of how to enable it.

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

When doing cardiac simulations, you’d think heart-shaped models would be ideal. However, for many basic science projects, a slab-shaped model with various regions of various shapes is more desirable. This allows isolation of geometry to answer a specific question. Historically people have used all sorts of tools to do this. Recently I’ve actually been using OpenSCAD to mock things up and make flat images, which I then massage through ImageJ and GIMP until I get something I can feed into the voxel-based mesher Tarantula.

This is really suboptimal, though. There must be some sort of constructive geometry modeler out there like OpenSCAD that will do proper volume meshes. OpenSCAD is really for surface meshes, but it’s so very easy to make the shapes I want in it. To that end I’ve been searching for FOSS CSG software, and I’m now trying the first one I found that has promise — BRL-CAD. I’ll post more as I try it out.

EDIT: So far so good the MGED editor in BRL-CAD seems to be WAY more powerful than OpenSCAD, much as I love OpenSCAD. I will post some designs as I get the hang of it.

Lately, with my 3d printer to inspire me, I’ve been thinking of all sorts of household gadgets that could improve on the ones I have. This morning, I was thinking about how we never seem to bother replacing the toilet paper on the holder, we just tend to set a new roll vertically on top of the empty roll. But wait — what if the toilet paper holder were vertical! We could just pull the old roll off and drop the new roll on! Brilliant! I rushed to google patent search, didn’t immediately see anything. But then I noticed when I typed ‘toilet paper holder v’ google auto-completed vertical. Sure enough, you can get them everywhere, including on Amazon. This will not stop me from designing and printing some for our house, though.

MakerGear Prusa Mendel Printing Hearts

Originally uploaded by brocktice

This was the last batch of large, orange hearts I made before running out of orange ABS filament. Now I’m printing smaller sets of 9 in clear PLA. They look really nice!

Getting close!