Re: [Lse-tech] Re: 10.31 second kernel compile

From: Anton Blanchard (anton@samba.org)
Date: Sat Mar 16 2002 - 00:27:30 EST


 
Hi,

> There are two dcache patches. The one I wrote based on Al Viro's
> suggestion for fast path walking is especially good for NUMA
> systems hit by cache bouncing (d_lookup is the main culprit in
> the dcache). Martin had some initial results that looked very
> good.

I gave the patch a go, here is the before and after for the kernel
compile benchmark. As you can see d_lookup and atomic_dec_and_lock
have both dropped. Since the main bottleneck for us is still the
ppc64 mm code, we didnt see a noticable drop in wall clock time.

It would be interesting to try the patch on a large specweb run,
Ive seen the dcache lock become a problem when running 8 way specweb.

Anton

before:
155912 total 0.0550
114562 .cpu_idle
 12615 .local_flush_tlb_range
  8476 .local_flush_tlb_page
  2576 .insert_hpte_into_group
  1980 .do_anonymous_page
  1813 .lru_cache_add
  1390 .d_lookup
  1320 .__copy_tofrom_user
  1140 .save_remaining_regs
   612 .rmqueue
   517 .atomic_dec_and_lock
   492 .do_page_fault
   444 .copy_page
   438 .__free_pages_ok
   375 .set_page_dirty
   350 .zap_page_range
   314 .schedule
   270 .__find_get_page
   245 .page_cache_release
   233 .lru_cache_del
   231 .hvc_poll
   215 .sys_brk

after:
152844 total 0.0539
113527 .cpu_idle
 12740 .local_flush_tlb_range
  7701 .local_flush_tlb_page
  2564 .insert_hpte_into_group
  2099 .do_anonymous_page
  1780 .lru_cache_add
  1230 .__copy_tofrom_user
  1082 .save_remaining_regs
   581 .rmqueue
   486 .__free_pages_ok
   479 .do_page_fault
   465 .copy_page
   371 .zap_page_range
   333 .atomic_dec_and_lock
   332 .set_page_dirty
   286 .__find_get_page
   275 .__d_lookup
   263 .path_lookup
   250 .page_cache_release
   221 .lru_cache_del
   218 .sys_brk
   215 .__flush_dcache_icache
-
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This archive was generated by hypermail 2b29 : Sat Mar 23 2002 - 22:00:11 EST