Speeding Up Slow Sums – Faster BSD Checksums

I recently made some changes to the Entangle archive that required a good majority of the archive to be checksum reverified. That’s about 200 TB worth of checksums. Even with six systems running parallel, and RAIDs hitting 600 MB/s, it still takes a while.

One thing I noticed was that the I/O rate while the sums were being performed was ~210 MB/s. A respectable speed, but cp’ing a file from the RAID to to /dev/null results in ~600 MB/s. So either my CPU was too slow or the ‘sum’ operation wasn’t as efficient as it could be. Continue reading “Speeding Up Slow Sums – Faster BSD Checksums”

Project Entangle

Project Entangle is Koherence’s internal platform for developing various media technologies. It began as a test bed for investigating how TiVo-style trick modes could be implemented using HTTP Live Streaming. Since then Project Entangle has blossomed into a collection of platforms.

The Entangle DVR platform supporting in-home and out-of-home playback is currently being alpha tested, with users watching shows on iPhones, iPads and AppleTVs. Another platform variant powers the SFBayATSC ATSC broadcast monitoring system. Continue reading “Project Entangle”

Just What Is High Definition?

I recently read a newsgroup thread that started with someone asking just what high definition was. The thread wound in some surprising ways, with individuals asserting, among other things, that anything 16:9 was high definition and that 480i digital content was high definition (while presumably 480i analog was not). I suspect most of you wouldn’t agree. After all, we all know 720p and 1080i are HD while anything less is SD, right? Well things aren’t quite so clear cut.

Continue reading “Just What Is High Definition?”

The Tickless Linux Kernel and Power Consumption

Those of you who’ve been following in-koherence know that I always keep power consumption in mind and frequently look into what’s driving my electricity bill. I recently went on another round of power misering at Koherence. After a bit of head-scratching, it turns out that running operating systems without tickless kernel support was an unexpected source of power drain. Continue reading “The Tickless Linux Kernel and Power Consumption”

Windows 10 Insomnia

This blog is a bit off-topic for in-koherence, but dealing with Windows 10’s inability to sleep through the night has been incredibly frustrating. Apparently it’s been for quite a few others too, so I decided to share my experience and ultimate solution (which fortunately did not involve burning my laptop.)

Since upgrading to Windows 10, I’ve come into the office on a couple occasions to find my laptop powered on. The first couple times I figured I must have forgotten to hibernate the system before leaving. But I was pretty sure I hibernated the system last night before going to bed…so what was it doing on? Continue reading “Windows 10 Insomnia”