[squeak-dev] The Inbox: Chronology-Core-eem.22.mcz
Levente Uzonyi
leves at caesar.elte.hu
Sat Jan 12 12:56:23 UTC 2019
On Fri, 11 Jan 2019, David T. Lewis wrote:
> On Sat, Jan 12, 2019 at 02:45:17AM +0100, Levente Uzonyi wrote:
>> On Fri, 11 Jan 2019, David T. Lewis wrote:
>>
>> >On Sat, Jan 12, 2019 at 12:32:51AM +0100, Levente Uzonyi wrote:
>> >>Since this thread is about optimization, I just had to chime in.
>> >>On 64-bit Spur, I measured ~12.5x speedup for #getSeconds which is
>> >>impressive. It can increased further by returning the value of the first
>> >>expression.
>> >>Also, I think the calculation is overcomplicated and the whole method
>> >>seems to be equivalent to:
>> >>
>> >> ^utcMicroseconds // 1000000 + localOffsetSeconds \\ 86400
>> >
>> >The implementation is simpler, but it seems to be a bit slower when I
>> >measure it (DateAndTime>>asSeconds changed versus Chronology-Core-ul.21
>> >on 64-bit Spur image).
>>
>> I guess you meant #getSeconds not #asSeconds.
>>
>> >
>> >I tested with this:
>> >
>> > dt := DateAndTime now.
>> > Time millisecondsToRun: [ 100000000 timesRepeat: [dt getSeconds ]].
>>
>> That is really interesting. Do you have numbers?
>>
>> Here's my benchmark:
>>
>> | d |
>> d := DateAndTime now.
>> (1 to: 5) collect: [ :run |
>> [ 1 to: 100000000 do: [ :i | d getSeconds ] ] timeToRun ]
>> "Original ==> #(3449 3416 3430 3430 3435)"
>> "Simplified ==> #(2538 2537 2566 2522 2558)"
>>
>> I thought that perhaps the negative offset can affect the results, but no,
>> it's the same with -7 * 3600 as offset.
>
> I was wrong, your simplified version *is* faster.
>
> Here is what I get:
>
> "Original:"
>
> Time millisecondsToRun: [ 100000000 timesRepeat: [dt getSeconds ]].
> "==> 4207"
>
> | d |
> d := DateAndTime now.
> (1 to: 5) collect: [ :run |
> [ 1 to: 100000000 do: [ :i | d getSeconds ] ] timeToRun ]
> "==> #(3706 3726 3725 3713 3689)"
>
> "Simplified:"
>
> Time millisecondsToRun: [ 100000000 timesRepeat: [dt getSeconds ]].
> "==> 3623"
>
> | d |
> d := DateAndTime now.
> (1 to: 5) collect: [ :run |
> [ 1 to: 100000000 do: [ :i | d getSeconds ] ] timeToRun ]
> "==> #(3165 3173 3174 3173 3222)"
>
> So your simplified version is both simpler and faster.
>
> Please commit it to trunk :-)
Great! I'll wait for Eliot's response, so that all the changes can be
pushed in one commit.
Levente
>
> Thanks,
> Dave
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