Re: NCL performance

Fan,

I was able to verify that the timiing difference happened between versions 5.1.1 and 5.2.0.
You're right: the issue is with ut_inv_calendar and not the loop.

It's hard to narrow down the problem at the moment, because in 5.2.0, we started using
Udunits-2, and had to change the code to reflect the new interface. It's possible that Udunits-2
is the issue, and not NCL, but I'm not certain.

I will submit a ticket on this, but it's going to be a low priority right now.

--Mary

On Nov 30, 2010, at 9:01 AM, Fan Fang wrote:

> Hi Mary,
>
> I was able to reproduce the problem with the following simple script.
> It largely resembles what was the most suspicious part of the code that
> slowed down with 5.2.1. It does a calendar conversion and an assignment
> in a loop. It doesn't look like that the do-loop itself slowed down.
>
> Typically it is a 4-second run for 5.1.1, but >15 seconds for 5.2.1.
>
> Thanks.
>
> -Fan
>
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
> begin
> x=new(1000,double)
> y=new(1000,double)
> wcStrtLooping = systemfunc("date")
> yyyy = 2002
> mm = 11
> dd = 18
> hh = 5
> nn = 0
> ss = 0
> do i=0,999
> x@units = "days since 1900-01-01 00:00:00"
> x(i) = ut_inv_calendar(yyyy,mm,dd,hh,nn,ss,x@units,0)
> if(i.gt.100) then
> y(i) = 1.0
> else
> y(i) = 0.0
> end if
> end do
> wallClockElapseTime(wcStrtLooping, "Complete loop", 0)
> end
>
>
> Mary Haley wrote:
>> Hi Fan,
>>
>> We need more information to see if there could be an issue.
>>
>> Please insert calls to "wallClockElapseTime in various sections in your script, and then rerun the script
>> to get more timing results. There are some examples here:
>>
>> http://www.ncl.ucar.edu/Document/Functions/Contributed/wallClockElapseTime.shtml
>>
>> This will help us narrow down where the problem is. Some key areas, as Dennis pointed out,
>> could have something to do with file I/O. It would be good to put these calls around
>> functions that are dealing with large arrays, and any calls to "addfile". Also, any
>> calls to a graphics routine might be a problem area.
>>
>> Thanks,
>>
>> --Mary
>>
>>
>> On Nov 29, 2010, at 11:55 AM, Fan Fang wrote:
>>
>>
>>>> uname -a
>>>>
>>> Linux discette 2.6.18-194.11.3.el5PAE #1 SMP Mon Aug 30 17:02:48 EDT
>>> 2010 i686 i686 i386 GNU/Linux
>>>
>>> What I did was to install the two versions (below) at the same location,
>>> and doing the same command-line (same input and output paths) using the
>>> same script. I added "time" in front the command-line. Results below.
>>> Let me know if you need more info. Thanks.
>>>
>>> -Fan
>>>
>>> ncl_ncarg-5.2.1.Linux_RedHat_i686_nodap_gcc412.tar.gz:
>>> 172.341u 1.212s 2:54.65 99.3% 0+0k 0+0io 0pf+0w
>>>
>>> ncl_ncarg-5.1.1.Linux_i686_gcc412.tar.gz:
>>> 50.035u 0.579s 0:50.87 99.4% 0+0k 0+0io 0pf+0w
>>>
>>> Dennis Shea wrote:
>>>
>>>> There should be no performance difference.
>>>> All 5.2.1 updates are listed at:
>>>> http://www.ncl.ucar.edu/current_release.shtml
>>>>
>>>> [1] If your files are on a NFS mounted file system, perhaps the
>>>> network was having issues.
>>>>
>>>> [2] Whenever, you post a comment or question like this one,
>>>> please include the output from
>>>>
>>>> %> uname -a
>>>>
>>>> THX
>>>>
>>>> On 11/29/10 9:12 AM, Fan Fang wrote:
>>>>
>>>>
>>>>> With NCL 5.2.1, we noticed a factor of ~3 reduction in performance with
>>>>> a x-y plot script. Our previous (and better performed) NCL version was
>>>>> 5.1.1. Is this expected?
>>>>>
>>>>> The script is plotting time series. There are quite a bit array
>>>>> manipulations in script. We haven't yet compared other scripts.
>>>>>
>>>>> -Fan
>>>>> _______________________________________________
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>
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Received on Wed Dec 1 15:03:44 2010