ipmctl MediaReads and MediaWrites vs. 256B granularity

[kanwu...@gmail.com]

Hi there,

I have a question related to media counters reported by ipmctl vs. PMEM 256B granularity:

• does MediaReads and MediaWrites counters  count the access amplification?
• in other words, assuming there is a 64B load to the DIMM (and I assume it will be amplified to a 256B load), then would the counter count 4 x 64B?

thank you

Kan

[Andy Rudoff]

This question was answered on our Slack channel.  Copying the answer here so it pops up in future searches...

Our media reads stat is in cachelines, So you will see a 4X amplification on our current Optane PMem products. Typically for writes you will see 2X but sometimes more or less depending on merging of writes. We do have a 256B read buffer so sequential cachelines might hit that buffer and not result in an amplification.