dcache RCU reduces system time for kernel compile by 10%

From: Martin J. Bligh (fletch@aracnet.com)
Date: Sat Sep 21 2002 - 15:09:12 EST


Installing dcache rcu drops system time for a kernel compile
from 52.7s to 47.3s - a little better than 10% reduction.
Total elapsed time doesn't change much, but I think this is
due to the lack of parallelism in the benchmark ... I need to
start running 32 parallel kernel compiles ;-)

Results were from a 16 cpu NUMA-Q. Comparison done on 2.5.36-mm1

Profile head before RCU:

  6964 do_anonymous_page
  4297 .text.lock.namei
  4189 page_remove_rmap
  2261 page_add_rmap
  2245 __generic_copy_from_user
  2217 .text.lock.dec_and_lock
  1685 vm_enough_memory
  1539 zap_pte_range
  1503 file_read_actor
  1389 rmqueue
  1139 find_get_page
  1074 get_empty_filp
  1063 do_no_page
   975 link_path_walk
   863 __fput
   838 path_lookup
   833 __free_pages_ok
   810 atomic_dec_and_lock
   793 __d_lookup
   737 do_page_fault
   670 .text.lock.file_table
   593 dput
   577 pte_alloc_one
   554 __generic_copy_to_user

profile head after RCU:

  6841 do_anonymous_page
  4171 page_remove_rmap
  2423 __generic_copy_from_user
  2321 page_add_rmap
  2247 d_lookup
  1773 vm_enough_memory
  1566 zap_pte_range
  1527 file_read_actor
  1342 rmqueue
  1281 .text.lock.file_table
  1153 find_get_page
  1149 get_empty_filp
  1049 do_no_page
   891 atomic_dec_and_lock
   775 do_page_fault
   752 __free_pages_ok
   667 follow_mount
   549 __fput
   535 pte_alloc_one
   529 do_generic_file_read
   521 path_lookup
   517 schedule
   509 release_pages
   504 do_softirq

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