kvm: memslots: replace heap sort with an insertion sort pass
memslots is a sorted array. When a slot is changed, heapsort (lib/sort.c) would take O(n log n) time to update it; an optimized insertion sort will only cost O(n) on an array with just one item out of order. Replace sort() with a custom sort that takes advantage of memslots usage pattern and the known position of the changed slot. performance change of 128 memslots insertions with gradually increasing size (the worst case): heap sort custom sort max: 249747 2500 cycles with custom sort alg taking ~98% less then original update time. Signed-off-by:Igor Mammedov <imammedo@redhat.com> Signed-off-by:
Paolo Bonzini <pbonzini@redhat.com>
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1d4e7e3c
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