Community
cancel
Showing results for 
Search instead for 
Did you mean: 
liangyang
Beginner
140 Views

How to copy data to PMem by I/OAT without DCA?

I am doing an experiment that using I/OAT DMA in CPU GOLD 5218 by SPDK to copy data from DRAM to PMem. In contrast to copy from DRAM to DRAM, it is necessary for PMem to flush the cache line after I/OAT DMA task is done.  I think the flush instruction may bring some performance penalty,so I want to close the feature of I/OAT named DCA which allows I/O to place data directly into CPU cache. How can I close the DCA appropriately in CPU GOLD 5218?

0 Kudos
5 Replies
BrusC_Intel
Moderator
119 Views

Hello, liangyang.


Thank you for posting in the Intel Community Support forum.


Seeing that your questions involve Intel® Optane™ Persistent Memory, I will move your thread to that specific community section so you can get assistance as soon as possible.


Best regards,


Bruce C.

Intel Customer Support Technician


SergioS_Intel
Moderator
96 Views

Hello liangyang,


Thank you for contacting Intel Customer Support.

 

Please allow us to check on your question and we will get back as soon as possible.


Best regards,

Sergio S.

Intel Customer Support Technician


For firmware updates and troubleshooting tips, visit :https://intel.com/support/serverbios


AdrianM_Intel
Moderator
68 Views

Hello liangyang,


Thank you for your patience.


If your setup is using remote access (basically anything outside of direct memory bus access) then you would need to disable I/OAT. Some systems have this available in the BIOS (either just DCA or I/OAT completely)


If the system has PMEM in App-Direct/Storage mode and it is on the Memory Bus/Controller (like you are trying to do periodic copies from the DRAM to the PMEM), you should be able to do this copy without flushing the cache using methods that are described here:


https://pmem.io/pmdk/libpmem2/


Regards,


Adrian M.

Intel Customer Support Technician



SergioS_Intel
Moderator
55 Views

Hello liangyang,


We are following your case and we would like to know if the information provided in our previous post was useful for you.


Please do not hesitate to contact us again if you need further assistance.


Best regards,

Sergio S.

Intel Technical Support Technician


For firmware updates and troubleshooting tips, visit :https://intel.com/support/serverbios


AdrianM_Intel
Moderator
39 Views

Hello liangyang,


We have not heard back from you, so we will close this inquiry. If you need further assistance, please post a new question.


Regards,


Adrian M.

Intel Customer Support Technician



Reply