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+--- Thread: Low GPU load for dictionary attack (/thread-4490.html)
Low GPU load for dictionary attack - oktar - 06-29-2015
Hello,
I have two hashing rigs, running on Ubuntu 14.04 LTS. Rig #1 has 4x Gigabyte R9 280x GPUs, Rig #2 has 4x MSI Twinfrozr III 7950 GPUs.
I use latest version of oclHashcat + hashtopus.
When I use mask brute force attack mode amdconfig shows continuous 99% load on every card, but for dictionary mode it drops to 70-95% and fluctuates.
Dictionary is quite big, 36 GB plain text, so I thought it's because hard drive. However I've been monitoring my hard drive (3 TB Seagate Barracuda 7200rpm) and I couldn't find any bottlenecks. During normal operation reading from drive takes maybe 5% of full speed, IOPS is on 30-50% level.
CPU is also good, 30-50% load.
It happens for both of my rigs.
So how comes it doesn't use full speed of my cards if there are no bottlenecks?
Well, at least I don't see them.
Any ideas?
RE: Low GPU load for dictionary attack - epixoip - 06-29-2015
You're not giving the GPU enough work to do. It is impossible to gain any acceleration with straight dictionary attacks against fast hashes unless you supply an amplifier.
http://hashcat.net/wiki/doku.php?id=frequently_asked_questions#how_to_create_more_work_for_full_speed