X86_64 msr cpuid refactor#5899
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## main #5899 +/- ##
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+ Coverage 83.00% 83.03% +0.02%
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Files 277 277
Lines 30106 30097 -9
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+ Hits 24989 24990 +1
+ Misses 5117 5107 -10
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Previously we were using Btree as an underlying data type for the `Cpuid` type. This required us to convert from `CpuId` type which is what KVM provides for transformations and then convert back into `CpuId` when we need to set it back to KVM. These conversions are unnecessary since the `CpuId` type can be used for the same purpose without any need for intermediate transition to Btree. This commit does this swap to using `CpuId` directly. In addition to removing a need for transition code, this change reduces the number of dynamic allocations/deallocations used in the Btree implementation. The only edge case of updating entries is handled by new `cpuid_insert` function which ensures we preserve the Btree de-duplicating quality. Since the number of entries in `CpuId` is quite low, doing linear searches will not cause any noticable performance change. Signed-off-by: Egor Lazarchuk <yegorlz@amazon.co.uk>
Similarly to the previous commit, replace Btree type for Msrs handling with kvm_bindings::Msrs to remove the unnecessary state transitions and memory allocations. Uniqueness of entries is preserved with `msrs_insert` function. Together with previous commit this reduces the binary sizy by ~30KiB and reduces the maximum RSS during `test_all_vcpus_online` test by 50-80 KiB Signed-off-by: Egor Lazarchuk <yegorlz@amazon.co.uk>
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Changes
Replace
Btreetype with direct underlyingCpuIdandMsrstypes to reduce the number of state transitions and memory allocations.This change makes the binary ~30KiB smaller and reduces the max RSS with 32 vcpus by 50-80 KiB.
Reason
Reduction in number of state transitions, memory allocations and code simplicity.
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how they are solving the problem in a clear and encompassing way.
in the PR.
CHANGELOG.md.Runbook for Firecracker API changes.
integration tests.
TODO.rust-vmm.