Re: mmap over nfs leads to excessive system load

[Kenny Simpson]

I tried the same test, but instead of ftruncate64, I simply did a pwrite64 to get the file
extended... and got 40M+ with mostly outbound traffic, and much less CPU usage..... 

Unfortunately, once my test file hit 4295065601, Bad Things (TM) started to happen.  The system
time went to 100% of a CPU, and the nfs traffic on that mount stopped.

I got an oprofile of the spinning system:
samples  %        symbol name
301039   27.9748  zap_pte_range
156234   14.5184  unmap_vmas
111760   10.3856  __bitmap_weight
103624    9.6295  _spin_lock
97063     9.0198  unmap_page_range
67011     6.2272  unmap_mapping_range
59382     5.5182  sub_preempt_count
51258     4.7633  zap_page_range
25235     2.3450  page_address
16768     1.5582  unmap_mapping_range_vma
13257     1.2319  debug_smp_processor_id
11594     1.0774  add_preempt_count

I also seem unable to kill the test process.

Any ideas?  (2**32 file size issue somewhere?)

-Kenny



	
		
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