Re: mmap over nfs leads to excessive system load

From: Kenny Simpson
Date: Wed Nov 16 2005 - 15:56:17 EST

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?)


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