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Avadhut Naik authored
To support GHES_ASSIST on Machine Check Architecture (MCA) error sources, a set of GHES structures is provided by the system firmware for each MCA error source. Each of these sets consists of a GHES structure for each MCA bank on each logical CPU, with all structures of a set sharing a common Related Source ID, equal to the Source ID of one of the MCA error source structures.[1] On SOCs with large core counts, this typically equates to tens of thousands of GHES_ASSIST structures for MCA under "/sys/bus/platform/drivers/GHES". Support for GHES_ASSIST however, hasn't been implemented in the kernel. As such, the information provided through these structures is not consumed by Linux. Moreover, these GHES_ASSIST structures for MCA, which are supposed to provide supplemental information in context of an error reported by hardware, are setup as independent error sources by the kernel during HEST initialization. Additionally, if the Type field of the Notification structure, associated with these GHES_ASSIST structures for MCA, is set to Polled, the kernel sets up a timer for each individual structure. The duration of the timer is derived from the Poll Interval field of the Notification structure. On SOCs with high core counts, this will result in tens of thousands of timers expiring periodically causing unnecessary preemptions and wastage of CPU cycles. The problem will particularly intensify if Poll Interval duration is not sufficiently high. Since GHES_ASSIST support is not present in kernel, skip initialization of GHES_ASSIST structures for MCA to eliminate their performance impact. [1] ACPI specification 6.5, section 18.7 Signed-off-by: Avadhut Naik <avadhut.naik@amd.com> Reviewed-by: Yazen Ghannam <yazen.ghannam@amd.com> Reviewed-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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