topic How should CHA counters be counted？ in Software Tuning, Performance Optimization & Platform Monitoring

How should CHA counters be counted？

Hz12 — Fri, 03 Jan 2025 12:39:28 GMT

Hi，

The Intel Xeon Gold 6256 processor was tested, which has 12 physical cores. When the CHA counters was used to monitor the uncore performance event UNC_CHA_TOR_OCCUPANCY.IO_HIT/MISS, it found that CHA0-23 could collect data (not all counters have a value). CHA counters with an index greater than 24 always have a value of 0. This processor has the same number of CHA counters as the number of physical cores, so should I count only the CHA0-11 counters? Or counting the CHA0-23 counter?

Re: How should CHA counters be counted？

McCalpinJohn — Mon, 27 Jan 2025 16:12:08 GMT

According to https://www.intel.com/content/www/us/en/products/sku/198655/intel-xeon-gold-6256-processor-33m-cache-3-60-ghz/specifications.html, the Xeon Gold 6256 processor has 33 MiB of L3 cache. For the SKX and CLX generations, each L3 "slice" is 1.375 MiB, so 33 MiB total implies that 24 L3 slices are active.

So there is no problem -- measure and use results from CHAs 0 to 23.