Re: mmap over nfs leads to excessive system load

[William Lee Irwin III <wli@holomorphy.com>]

On Tue, Nov 15, 2005 at 03:47:30PM -0800, Kenny Simpson wrote:
> CPU: P4 / Xeon with 2 hyper-threads, speed 2658.47 MHz (estimated)
> Counted GLOBAL_POWER_EVENTS events (time during which processor is not stopped) with a unit mask
> of 0x01 (mandatory) count 100000
> samples  %        symbol name
> 412585   14.6687  find_get_pages_tag
> 343898   12.2267  mpage_writepages
> 290144   10.3155  release_pages
> 288631   10.2617  unlock_page
> 286181   10.1746  pci_conf1_write
> 267619    9.5147  clear_page_dirty_for_io
> 128128    4.5554  __lookup_tag
> 120895    4.2982  page_waitqueue
> 52739     1.8750  _spin_lock_irqsave
> 43623     1.5509  skb_copy_bits
> 30157     1.0722  __wake_up_bit
> 29973     1.0656  _read_lock_irqsave

67%, or 2/3 of the samples, are in the top 6 functions. Have you tried
instruction-level profiling? It would be interesting to see what
codepaths within the functions are the largest offenders.


-- wli
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