Author Topic: Thread-concurrency for Radeon HD 5450  (Read 2862 times)

Offline AZ-Miner

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Thread-concurrency for Radeon HD 5450
« on: April 04, 2013, 05:07:09 PM »
Where can I find the best thread-concurrency for my Radeon HD 5450? I tried searching google with key words but no results.

Offline zyndarius

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Re: Thread-concurrency for Radeon HD 5450
« Reply #1 on: April 09, 2013, 06:39:50 PM »
Same thing here but for a radeon hd 4850, I do not even know what thread currency means. Have not found info about it =(
LTC: LbBr8PVzMPv1dVj2zUxG9Pozhr3KdBtqY7

Offline Turix

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Re: Thread-concurrency for Radeon HD 5450
« Reply #2 on: April 09, 2013, 07:14:06 PM »
Thread concurrency is essentially the number of individual Scrypt processes that will be run at the same time on your hardware, this needs to be high enough to fully stress the core without overloading it.

Generally speaking for a AMD cards you want to use numbers that are between 4 and 5 times the number of shaders on the card, whilst also being a factor of 64. Some ranges I would suggest testing for the cards you are both using would be:

HD 5450 (80 Shaders): 320, 384, 448
HD 4850 (800 Shaders): 3200-4032 (try those two and some in-between, just remember to make them divisible by 64)

With the HD 5450 I would also suggest trying a lower worksize (64 or 128) as it only has a narrow memory bus width (64-bit vs 256bit on most cards). From what I've seen I would say the HD 5450 should be able to do around 15Khash/s depending on the exact model/clock (speed/ratio) and the HD 4850 possible in the 100-125 Khash/s region, although I've got a bit less knowledge of 4xxx series cards.

As a bit of additional reading, this thread on Bitcointalk goes into a bit of depth on the issue.

Offline zyndarius

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Re: Thread-concurrency for Radeon HD 5450
« Reply #3 on: April 09, 2013, 09:19:56 PM »
Thank you very much for your explanation. I am deeply thankful.

One more question about the values used. Those are when one wants to use the GPU 100% for mining right. Because I have noticed when I setup for instance 3200 almost my whole video ram gets consumed and I am unable to use my desktop for example to play a video. Or am I doing something wrong and the cgminer auto-regulates itself to let media player classic (for instance) use video memory?
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Offline Turix

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Re: Thread-concurrency for Radeon HD 5450
« Reply #4 on: April 09, 2013, 09:34:45 PM »
Thank you very much for your explanation. I am deeply thankful.

One more question about the values used. Those are when one wants to use the GPU 100% for mining right. Because I have noticed when I setup for instance 3200 almost my whole video ram gets consumed and I am unable to use my desktop for example to play a video. Or am I doing something wrong and the cgminer auto-regulates itself to let media player classic (for instance) use video memory?

Interesting, may I ask what versions of CGMiner and AMD Drivers you are running? Because I am running a 5870 using CGMiner 2.11.3/AMD 13.3 Beta 3 and CGMiner doesn't use any real amount of system memory (~25MB), and thats with 6144 for my TC.

On a side note, CGMiner is always going to hit your GPU hard and depending on what you have set the intensity to it may make your desktop unusable - try testing it in the range of 12-18 and see what balance of usability and hash rate you feel comfortable with. CGMiner also has a dynamic intensity mode (set intensity to d), however this needs tweaking through "--gpu-dyninterval" to be able to get usable hash rates (try values between 8-128, 32 worked well for me); this is the length of time (in ms) that the GPU can be blocked for, lower numbers allow the GPU to be used by other applications more readily.

Edit: As a side note my the details of my HD 5870 (855/1215):

Code: [Select]
start /low cgminer-low --config ltc-pools.conf --queue 0 --scrypt --shaders 1600 --intensity 19 --lookup-gap 2 --worksize 256 --gpu-threads 1 --thread-concurrency 6144 -d 1
The -d 1 is because I have two outside of crossfire, I don't ever mine on the "zero" card as it use it for gaming (plus its fan sounds like a jet engine).
« Last Edit: April 09, 2013, 09:54:29 PM by Turix »