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CXL Memory Device SW Guide [1] rev1.0 2.11.2 provides instruction on how to calculate latency and bandwidth for CXL memory device. Calculate minimum bandwidth and total latency for the path from the CXL device to the root port. The QTG id is retrieved by providing the performance data as input and calling the root port callback ->get_qos_class(). The retrieved id is stored with the cxl_port of the CXL device. For example for a device that is directly attached to a host bus: Total Latency = Device Latency (from CDAT) + Dev to Host Bus (HB) Link Latency + Generic Port Latency Min Bandwidth = Min bandwidth for link bandwidth between HB and CXL device, device CDAT bandwidth, and Generic Port Bandwidth For a device that has a switch in between host bus and CXL device: Total Latency = Device (CDAT) Latency + Dev to Switch Link Latency + Switch (CDAT) Latency + Switch to HB Link Latency + Generic Port Latency Min Bandwidth = Min bandwidth for link bandwidth between CXL device to CXL switch, CXL device CDAT bandwidth, CXL switch CDAT bandwidth, CXL switch to HB bandwidth, and Generic Port Bandwidth. [1]: https://cdrdv2-public.intel.com/643805/643805_CXL%20Memory%20Device%20SW%20Guide_Rev1p0.pdf Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by: Dave Jiang <dave.jiang@intel.com> Link: https://lore.kernel.org/r/170319624458.2212653.13252496567443656371.stgit@djiang5-mobl3 Signed-off-by: Dan Williams <dan.j.williams@intel.com> |
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| .. | ||
| core | ||
| acpi.c | ||
| cxl.h | ||
| cxlmem.h | ||
| cxlpci.h | ||
| Kconfig | ||
| Makefile | ||
| mem.c | ||
| pci.c | ||
| pmem.c | ||
| pmu.h | ||
| port.c | ||
| security.c | ||