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author | Paolo Bonzini <pbonzini@redhat.com> | 2015-05-21 15:12:29 +0200 |
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committer | Paolo Bonzini <pbonzini@redhat.com> | 2015-06-05 17:09:58 +0200 |
commit | db94604b20278c1dc227a04e4c564d80230e6c3f (patch) | |
tree | e50ac998678fe6af599a7e52054556b978fb9c4a /stubs/reset.c | |
parent | e4afbf4fb4d026510700cb40bb72dea9aef14e3b (diff) |
exec: optimize phys_page_set_level
phys_page_set_level is writing zeroes to a struct that has just been
filled in by phys_map_node_alloc. Instead, tell phys_map_node_alloc
whether to fill in the page "as a leaf" or "as a non-leaf".
memcpy is faster than struct assignment, which copies each bitfield
individually. A compiler bug (https://gcc.gnu.org/PR66391), and
small memcpys like this one are special-cased anyway, and optimized
to a register move, so just use the memcpy.
This cuts the cost of phys_page_set_level from 25% to 5% when
booting qboot.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'stubs/reset.c')
0 files changed, 0 insertions, 0 deletions