About "time yum --help".

[Vinicius]

Nifty Hat Mitch escreveu:
> On Wed, Jan 12, 2005 at 03:43:44PM -0200, Vinicius wrote:
> 
>>Mogens Kjaer escreveu:
>>
>>>Vinicius wrote:
> 
> ...
> 
>>>>time yum --help takes:
>>>>real    0m7.125s
> 
> ...
> 
>>>>Why, please?
> 
> 
> Why so long or why so short?
> 
> 
>>>You can do a:
>>>strace -t -o/tmp/yum.log yum --help
> 
> 
>>I see several lines as "open("/usr/lib/python2.3/lib-dynload/yum.so", 
>>O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory)" for example.
>>Is it relevant?
> 
> 
> The open() ENOENT calls are commonly quick.
> strace has flags that help you time system calls (-tt -r -T).
> 
> This open() returns ENOENT.
> 
>   open("/usr/lib/python23.zip/sitemodule.so",.... <0.000013>
> 
> So to me 0.000013 is not relevant to me unless there is a pile of them.
> 
> Run it through strace twice in a row with different log files and the
> additional time information flags then match up the files (vim -d
> might work) and match the system calls.
> 
> Something like... presents me with hints that I think answer
> the question.
>     # time yum -help
>     ....
>     real    0m2.097s
>     user    0m0.200s
>     sys     0m0.085s
>     # time yum -help
>     ....
>     real    0m0.349s
>     user    0m0.205s
>     sys     0m0.026s
> 
> This quickly tells me that a lot of time
> is being spent waiting on my disk IO.   YMMV....
> 
> 

Cool tip.

Did you see the report from John Swartzentruber about the connect and 
send system calls? They do something?