Author Topic: How to achieve fastest save times.  (Read 566 times)

John DeLonghi

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How to achieve fastest save times.
« on: December 28, 2017, 09:16:09 AM »
This has been discussed in another thread, but I thought it might be worth having a dedicated thread here, especially now the auto save feature is available, as we'll want to dump the full internal RAM to card/USB as quickly as possible.

In my testing, I've not managed to surpass 36MB/sec, so I'm assuming this is the fastest transfer rate currently possible with firmware 0.2.3 beta?

I can achieve this speed with a USB 3 stick, XQD card in a USB adapter and a Sandisk Extreme Pro Class 10 SD card in the slot.

I don't think there's any difference in transfer rate between the internal slot and the USB interface.

Any other observations from anyone?


tesla500

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Re: How to achieve fastest save times.
« Reply #1 on: December 28, 2017, 12:39:35 PM »
You're correct, on 0.2.3 beta you'll get about 35MB/s max. This is limited by code provided by the CPU vendor TI, we'll be working on speeding it up, but Etherent is priority right now for development. It should be possible to get much faster save speeds, perhaps up to 200-250MB/s over eSATA, once things are optimized.

John DeLonghi

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Re: How to achieve fastest save times.
« Reply #2 on: December 31, 2017, 03:07:48 AM »
Will the USB speed increase as well as eSATA?

tesla500

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Re: How to achieve fastest save times.
« Reply #3 on: January 01, 2018, 05:00:23 AM »
Will the USB speed increase as well as eSATA?

Somewhat, but not as much as SATA. It would max out around the same speed as you get from your PC to the drive, perhaps 30-40MB/s

John DeLonghi

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Re: How to achieve fastest save times.
« Reply #4 on: January 01, 2018, 05:15:13 AM »
Where's the bottleneck when using the USB interface? I'm getting speeds much higher than 40MB/s between my PC and storage devices using USB 3. I'm getting 200MB/s easily using a fast flash drive.

The eSata interface - what types of storage devices will it support? Could I plug in an eSata HDD and it would be powered from the camera, for instance?

Loial

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Re: How to achieve fastest save times.
« Reply #5 on: January 02, 2018, 03:34:17 PM »
TI's implementation of Linux and the video pipeline requires a memcpy from video buffer memory into the kernel space. This saturates the CPU making the whole copy slow.

Right now we're looking into making our own gstreamer pipeline element that can use DMA to copy to the drive instead. This will be in the works as a test once we have network control at least prototyped.