Re: Drive performance bottleneck

[Ian Godin]

On Feb 2, 2005, at 7:56 PM, Bernd Eckenfels wrote:

> In article <c4fc982390674caa2eae4f252bf4fc78@xxxxxxxxxxxxxxxx> you 
> wrote:
> >  Below is an oprofile (truncated) of (the same) dd running on 
> > /dev/sdb.
>
> do  you also have the oprofile of the sg_dd handy?
>
> Greetings
> Bernd

  Just ran it on the sg_dd (using /dev/sg1):

CPU: P4 / Xeon, speed 3402.13 MHz (estimated)
Counted GLOBAL_POWER_EVENTS events (time during which processor is not 
stopped) with a unit mask of 0x01 (mandatory) count 10
0000
samples  %        symbol name
2145136  89.7474  __copy_to_user_ll
64720     2.7077  lock_kernel
17883     0.7482  mark_offset_tsc
16212     0.6783  page_address
8091      0.3385  schedule
5380      0.2251  timer_interrupt
5314      0.2223  _spin_lock
5311      0.2222  mwait_idle
4034      0.1688  sysenter_past_esp
3569      0.1493  do_anonymous_page
3530      0.1477  apic_timer_interrupt
3368      0.1409  _spin_lock_irqsave
3150      0.1318  sg_read_xfer
3043      0.1273  kmem_cache_alloc
2590      0.1084  find_busiest_group
2553      0.1068  scheduler_tick
2319      0.0970  __copy_from_user_ll
2299      0.0962  sg_ioctl
2131      0.0892  irq_entries_start
1905      0.0797  sys_ioctl
1773      0.0742  copy_page_range
1678      0.0702  fget
1648      0.0689  __switch_to
1648      0.0689  scsi_block_when_processing_errors
1632      0.0683  sg_start_req
1569      0.0656  increment_tail
1511      0.0632  try_to_wake_up
1506      0.0630  update_one_process
1454      0.0608  fput
1397      0.0584  do_gettimeofday
1396      0.0584  zap_pte_range
1371      0.0574  recalc_task_prio
1357      0.0568  sched_clock
1352      0.0566  sg_link_reserve
1282      0.0536  __elv_add_request
1229      0.0514  kmap_atomic
1195      0.0500  page_fault

  Oddly enough it appears to also be copying to user space...

     Ian.

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