Messages in this thread | | | Date | Wed, 02 Jul 2003 15:53:24 -0700 | From | "Martin J. Bligh" <> | Subject | Overhead of highpte |
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Some people were saying they couldn't see an overhead with highpte. Seems pretty obvious to me still. It should help *more* on the NUMA box, as PTEs become node-local.
The kmap_atomic is, of course, perfectly understandable. The increase in the rmap functions is a bit of a mystery to me.
M.
Kernbench: (make -j vmlinux, maximal tasks) Elapsed System User CPU 2.5.73-mm3 45.38 114.91 565.81 1497.75 2.5.73-mm3-highpte 46.54 130.41 566.84 1498.00
(note system time)
1480 9.1% total 1236 52.7% page_remove_rmap 113 18.5% page_add_rmap 90 150.0% kmap_atomic 89 54.6% kmem_cache_free 45 15.0% zap_pte_range 37 0.0% kmap_atomic_to_page 28 87.5% __pte_chain_free 26 216.7% kunmap_atomic 17 13.4% release_pages 12 10.5% file_move 11 42.3% filemap_nopage 10 13.7% handle_mm_fault ... -10 -16.1% generic_file_open -10 -5.2% atomic_dec_and_lock -13 -2.4% __copy_to_user_ll -13 -3.7% find_get_page -13 -7.0% path_lookup -21 -2.6% __d_lookup -36 -78.3% page_address -49 -74.2% pte_alloc_one -104 -2.2% default_idle
SDET 32 (see disclaimer) Throughput Std. Dev 2.5.73-mm3 100.0% 0.8% 2.5.73-mm3-highpte 95.3% 0.1%
(highpte hung above 32 load).
971 5.5% total 399 3.9% default_idle 329 23.1% page_remove_rmap 124 15.6% page_add_rmap 119 94.4% kmem_cache_free 39 205.3% kmap_atomic 24 9.8% release_pages 21 131.2% __pte_chain_free 15 1500.0% kmap_atomic_to_page 13 76.5% __kmalloc 11 183.3% kunmap_atomic ... -10 -35.7% __copy_from_user_ll -10 -3.9% find_get_page -16 -11.7% .text.lock.filemap -16 -45.7% page_address -16 -18.2% atomic_dec_and_lock -40 -74.1% pte_alloc_one
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