MW with Dual GPUs - need Opti app still?

[DrPop]

Just an off question - since I have dual GPUs in this thing, it automatically crunches 2 MW WUs at a time...should I still use the opti-app which would then make it crunch 4 at a time? Just checking...

[Harley]

Just an off question - since I have dual GPUs in this thing, it automatically crunches 2 MW WUs at a time...should I still use the opti-app which would then make it crunch 4 at a time? Just checking...

I tried that a while ago. I never saw much of a difference. The cards were crunching twice as many WU's at a time but they were taking slightly more than twice as long to complete.

[DrPop]

OK, thanks Harley. I'll leave it on regular mode, then. Joker suggested switching to MW for a bit while the cred is good...so I've made the switch.

[Maxwell]

I tried that a while ago. I never saw much of a difference. The cards were crunching twice as many WU's at a time but they were taking slightly more than twice as long to complete.

In my experiences, the WUs take slightly less than twice as long running two at a time. Since it takes BOINC a non-zero amount of time to start a new WU, allowing two to run at once lets the card take advantage of that "idle" time by letting another WU use it. Which is why unsyncing your MW WUs when running two at a time is also helpful...

Another reason to use the app_info file: it allows you to set the priority of the GPU, making sure the CPU is always available to feed the GPU...

[Harley]

In my experiences, the WUs take slightly less than twice as long running two at a time. Since it takes BOINC a non-zero amount of time to start a new WU, allowing two to run at once lets the card take advantage of that "idle" time by letting another WU use it. Which is why unsyncing your MW WUs when running two at a time is also helpful...

Another reason to use the app_info file: it allows you to set the priority of the GPU, making sure the CPU is always available to feed the GPU...

I may have to give it another try. DrPop ignore me!

[DrPop]

Hehehe...OK. I may give it a try too - how do you set the priority of the GPU over the CPU in the opti app?

[Maxwell]

Hehehe...OK. I may give it a try too - how do you set the priority of the GPU over the CPU in the opti app?

Edit the cmdline to "p3 b-1" (quotes not included).

[Bryan]

Whether you run multiple wu at a time per card makes about a 2% difference. What DOES make a big difference is using the p3 b-1 in the opti app command line. That elevates the GPU priority to HIGH so it takes precedence over any CPU task and the GPU doesn't have to wait to get serviced. On most machines with high speed GPUs this makes a 6-8% difference.

[Maxwell]

And note that 2% is about 5k/day on a 5870...

[Harley]

And note that 2% is about 5k/day on a 5870...

I'm definitely gonna have to try it again!