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| -rw-r--r-- | Documentation/arm64/perf.txt | 85 |
1 files changed, 0 insertions, 85 deletions
diff --git a/Documentation/arm64/perf.txt b/Documentation/arm64/perf.txt deleted file mode 100644 index 0d6a7d87d49e..000000000000 --- a/Documentation/arm64/perf.txt +++ /dev/null @@ -1,85 +0,0 @@ -Perf Event Attributes -===================== - -Author: Andrew Murray <andrew.murray@arm.com> -Date: 2019-03-06 - -exclude_user ------------- - -This attribute excludes userspace. - -Userspace always runs at EL0 and thus this attribute will exclude EL0. - - -exclude_kernel --------------- - -This attribute excludes the kernel. - -The kernel runs at EL2 with VHE and EL1 without. Guest kernels always run -at EL1. - -For the host this attribute will exclude EL1 and additionally EL2 on a VHE -system. - -For the guest this attribute will exclude EL1. Please note that EL2 is -never counted within a guest. - - -exclude_hv ----------- - -This attribute excludes the hypervisor. - -For a VHE host this attribute is ignored as we consider the host kernel to -be the hypervisor. - -For a non-VHE host this attribute will exclude EL2 as we consider the -hypervisor to be any code that runs at EL2 which is predominantly used for -guest/host transitions. - -For the guest this attribute has no effect. Please note that EL2 is -never counted within a guest. - - -exclude_host / exclude_guest ----------------------------- - -These attributes exclude the KVM host and guest, respectively. - -The KVM host may run at EL0 (userspace), EL1 (non-VHE kernel) and EL2 (VHE -kernel or non-VHE hypervisor). - -The KVM guest may run at EL0 (userspace) and EL1 (kernel). - -Due to the overlapping exception levels between host and guests we cannot -exclusively rely on the PMU's hardware exception filtering - therefore we -must enable/disable counting on the entry and exit to the guest. This is -performed differently on VHE and non-VHE systems. - -For non-VHE systems we exclude EL2 for exclude_host - upon entering and -exiting the guest we disable/enable the event as appropriate based on the -exclude_host and exclude_guest attributes. - -For VHE systems we exclude EL1 for exclude_guest and exclude both EL0,EL2 -for exclude_host. Upon entering and exiting the guest we modify the event -to include/exclude EL0 as appropriate based on the exclude_host and -exclude_guest attributes. - -The statements above also apply when these attributes are used within a -non-VHE guest however please note that EL2 is never counted within a guest. - - -Accuracy --------- - -On non-VHE hosts we enable/disable counters on the entry/exit of host/guest -transition at EL2 - however there is a period of time between -enabling/disabling the counters and entering/exiting the guest. We are -able to eliminate counters counting host events on the boundaries of guest -entry/exit when counting guest events by filtering out EL2 for -exclude_host. However when using !exclude_hv there is a small blackout -window at the guest entry/exit where host events are not captured. - -On VHE systems there are no blackout windows. |