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indigo in multi gpu open cl mode works slower than in single-gpu mode

Posted: Mon Mar 23, 2020 11:31 pm
by wob
i found that indigo in multi gpu mode (two or more cards) works slower than with single card in open cl mode. i test it on multi gtx 1060 6gb rig (up to 4 cards) with pentium g4400 processor. any test scene with single gtx card renders faster than with two or more cards: single card has 99% gpu utilisation (with flat line of gpu utilisation graph located near 100% graph point), but each of two cards has around 33% of gpu utilisation with graphs looks like sharp peaks from 0% graph point to 50%.

configuration: asus z270-p / pentium g4400 / 4x gtx 1060 6gb/ 24gb ram / newest nvidia drivers.

Re: indigo in multi gpu open cl mode works slower than in single-gpu mode

Posted: Sun Mar 29, 2020 10:41 am
by fourzeronine
You have 4 modern graphics cards with a dual core CPU and only 16 lanes of pci total in the entire system. Your cpu is the bottleneck.