nimforum mirror - Difference in Nim Run time

ajaychat3 (orginal) [2025-03-03T09:18:12+01:00] view original

I am using Nim for about 4 years. I have an application designed which does some calculations using Times library. The calculations mainly involve converting text fields from CSV file into date for calculating the number of months/Days between two dates, adding dates, comparing dates etc. An example is given below

proc durMth*(d1:DateTime, d2:DateTime) : int {.inline.} =
var

NOM: int

NOM = ((d2.year - d1.year) * 12 + ord(d2.month) - ord(d1.month))

if d2.monthday < d1.monthday:

NOM -= 1

if (vRCD + vPT_O.years) <= sDateC:

xxx = yyyy

The application take around 45s to run on a specific count of records on linux OS.

Alongside I have the same application which does the same calculation using text fields without converting them into Dates. Everything else is the same otherwise. An example is given below.

proc durMth*(d1:string, d2:string) : int {.inline.} =
var

NOM: int

dat1, dat2: seq[string]

sep : string

sep = if contains(d1,"-"): "-" else : "/"

dat1 = split(d1,sep)

sep = if contains(d2,"-"): "-" else : "/"

dat2 = split(d2, sep)

NOM = (dat2[2].parseint - dat1[2].parseint) * 12 + dat2[1].parseint - dat1[1].parseint

if dat2[0].parseint < dat1[0].parseint:

NOM -= 1

return NOM

if addDur(vRCD, y = vPT_O) <= durDays(sDateC):

xxx = yyyy

This application take 25s to run on the same data on linux OS on the same computer. Both are compiled using similar compiler flags.

Another thing I have noticed that when both of these applications are run on windows or MAc, they take approx the same time.

I would like to understand the reasons for difference in speed on linux. Why the use of Times library is causing increase in run times on linux OS.

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12699 :: Difference in Nim Run time

NOM -= 1