Question I have installed a K80 to 7048GR-TR. I found the GPUDirect P2P(peer-to-peer) between the two GPU GK210 inside K80 is not getting expected performance. Is there a fix for this problem? Answer A: The ACS(access control services) need to be disabled for proper P2P bandwidth. The latest BIOS will disabled ACS of the PLX PCI-e switch inside the K80 to avoid the problem(Please contact tech support for BIOS later than BIOS 1.0c 2015/2/25). However, user is still encouraged to confirm ACSCtl is disabled in Linux due to the operating system can still enable ACS. Pleaes run lspci -vvv and make sure you get "ACSCtl: SrcValid-" instead of "ACSCtl: SrcValid+" for PLX PCI-e switch. If you get "ACSCtl: SrcValid+" for the PCI bridge: PLX Technology, run "setpci -s bus#:slot#.func# f2a.w=0000" to disable ACSCtl on the PLX switch. e.g. #setpci -s 03:08.0 f2a.w=0000 *assume 03:08.0 is the PLX pcie switch* run lspci -vvv to confirm ACSCtrl is disabled on PLX switch. #lspci -vvv | grep ACSCtrl ACSCtl: SrcValid- TransBlk- ReqRedir- CmpltRedir- UpstreamFwd- EgressCtrl- DirectTrans- ACSCtl: SrcValid- TransBlk- ReqRedir- CmpltRedir- UpstreamFwd- EgressCtrl- DirectTrans- ACSCtl: SrcValid- TransBlk- ReqRedir- CmpltRedir- UpstreamFwd- EgressCtrl- DirectTrans- ACSCtl: SrcValid- TransBlk- ReqRedir- CmpltRedir- UpstreamFwd- EgressCtrl- DirectTrans- ACSCtl: SrcValid- TransBlk- ReqRedir- CmpltRedir- UpstreamFwd- EgressCtrl- DirectTrans- ACSCtl: SrcValid- TransBlk- ReqRedir- CmpltRedir- UpstreamFwd- EgressCtrl- DirectTrans- the ACSCtl setting will be reset in next boot, so please schedule the system to do the same setting at every boot. Was this FAQ helpful? YES      NO Enter Comments Below: Note: Your comments/feedback should be limited to this FAQ only. For technical support, please send an email to support@supermicro.com.  Enter your email address below if you'd like technical support staff to reply:  Please type the Captcha (no space) X 6 C T FAQ Stats FAQ ID Related Category / Keyword Date Posted Code 20732 BIOS: - BIOS Setting Operating Systems: - Linux OS 05/18/15     Print Answer