[dtrace-discuss] dtrace wired issue

max at bruningsystems.com
Mon, 14 Jan 2008 22:12:35 -0000

Hi James,
James C. McPherson wrote:
> Aubrey Li wrote:
>
>> On Jan 14, 2008 8:52 PM, Sean McGrath - Sun Microsystems Ireland
>> <sean.mcgrath at sun.com> wrote:
>>
>>> Aubrey Li stated:
>>> < Every first time to run dtrace command after the system boot
up,
>>> < It takes a very long time to get response.
>>> < But the second time is OK, as follows:
>>> <
>>> < # time dtrace -l > /dev/null
>>> <
>>> < real    4m8.011s
>>> < user    0m0.116s
>>> < sys     0m2.420s
>>>
>>>   This first time is probably when the kernel is loading the dtrace
modules.
>>>   Though still seems slow, 4 minutes.
>>>     What kind of system (cpu speed etc) is the machine ?
>>>
>> # psrinfo -vp
>> The physical processor has 2 virtual processors (0 1)
>>   x86 (GenuineIntel 10674 family 6 model 23 step 4 clock 2400 MHz)
>>         Intel(r) CPU                  @ 2.40GHz
>>
>> So, I failed to understand the modules loading needs 4 minutes.
>>
>
>
> If you run "dtrace -l" with no args, *every* single loadable
> module on the system will be loaded, interrogated by dtrace
> and then unloaded if possible.
>
You mean every kernel module currently loaded will be interrogated.  Not
every kernel module on the system.  So _init/_info/_fini/attach/detach
should not enter into this.
max

> All those attach()es and detach()es need time, as does the
> probe collation.
>
>
>
> James C. McPherson
> --
> Senior Kernel Software Engineer, Solaris
> Sun Microsystems
> http://blogs.sun.com/jmcp	http://www.jmcp.homeunix.com/blog
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