Re: mmap over nfs leads to excessive system load
From: Trond Myklebust
Date: Wed Nov 16 2005 - 16:10:09 EST
On Wed, 2005-11-16 at 12:56 -0800, Kenny Simpson wrote:
> 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?)
Is this NFSv2?
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