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| author | Nicholas Piggin <npiggin@gmail.com> | 2024-02-21 20:08:31 +1000 |
|---|---|---|
| committer | Nicholas Piggin <npiggin@gmail.com> | 2024-05-24 08:57:50 +1000 |
| commit | c700b5e162208a0fa4211fc6d9dab271b1342640 (patch) | |
| tree | 794e2bd36806c77269fc4e3dff93e7f1d32fdbf3 /qemu-keymap.c | |
| parent | 70581940cabcc51b329652becddfbc6a261b1b83 (diff) | |
spapr: avoid overhead of finding vhyp class in critical operations
PPC_VIRTUAL_HYPERVISOR_GET_CLASS is used in critical operations like
interrupts and TLB misses and is quite costly. Running the
kvm-unit-tests sieve program with radix MMU enabled thrashes the TCG
TLB and spends a lot of time in TLB and page table walking code. The
test takes 67 seconds to complete with a lot of time being spent in
code related to finding the vhyp class:
12.01% [.] g_str_hash
8.94% [.] g_hash_table_lookup
8.06% [.] object_class_dynamic_cast
6.21% [.] address_space_ldq
4.94% [.] __strcmp_avx2
4.28% [.] tlb_set_page_full
4.08% [.] address_space_translate_internal
3.17% [.] object_class_dynamic_cast_assert
2.84% [.] ppc_radix64_xlate
Keep a pointer to the class and avoid this lookup. This reduces the
execution time to 40 seconds.
Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Diffstat (limited to 'qemu-keymap.c')
0 files changed, 0 insertions, 0 deletions