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No overhead is not the same, but specifying more bars than needed is
a) waste of memory (because a larger buffer for plugin communication need to be allocated)
and may lead to memory fragmentation
b) increases potential of CPU cache misses (which is significant issue as accessing on-chip cache on modern
computers is even 10x faster than RAM)
Frankly I was contemplating removing this 'number of bars' setting completely
so AB would decide what is 'correct' number of bars for each data source, depending
on data source specs, but frankly I am opponent of building software that 'knows better'
there is a group of power-users who need these settings. More tweakability always increases
number of support issues and that is inevitable. Till date I rather preferred having more
tweakability. Recently I got the impression that AB potential is rarely fully used
just because of too many settings. In today's world there is strong desire for the simplest
UI's and shortest learning curve. I can understand that.
At some point I may rethink things once again and re-code the database handling.
Best regards,
Tomasz Janeczko
amibroker.com
----- Original Message -----
From: "Paul Ho" <paul.tsho@xxxxxxxxx>
To: <amibroker@xxxxxxxxxxxxxxx>
Sent: Sunday, December 07, 2008 12:47 PM
Subject: [amibroker] Re: Speed Issues
> If there were 2 M bars specified in the database but only 1M bars
> are stored in a particular ticker, Is the overhead involved in
> loading this ticker the same as if 2M bars were stored?
> /Paul.
>
>
> --- In amibroker@xxxxxxxxxxxxxxx, "Tomasz Janeczko" <groups@xxx>
> wrote:
>>
>> For others experiencing same problem:
>> the reason was over-the-roof number of bars specified in File-
>>Database Settings.
>> There were 2 MILLION bars entered in 1-minute database, which is
>> 20x more than recommended setting of 100 000 bars.
>>
>> The IQFeed should be setup EXACTLY as shown in the video
>> http://www.amibroker.com/video/IQFeed.html
>>
>> Specifying 20x more "number of bars" causes 20x more overhead and
>> CPU cache misses because instead just using 3MB cache for one
> symbol at 100k bars,
>> 2 million bars it requires 62MB. This effectively means that your
> on-chip
>> CPU cache is flushed non-stop and that forces CPU to use much
> slower (10x) RAM memory.
>>
>> Best regards,
>> Tomasz Janeczko
>> amibroker.com
>> ----- Original Message -----
>> From: "Tomasz Janeczko" <groups@xxx>
>> To: <amibroker@xxxxxxxxxxxxxxx>
>> Sent: Friday, December 05, 2008 11:56 PM
>> Subject: Re: [amibroker] Re: Speed Issues
>>
>>
>> > Hello,
>> >
>> > Indeed the times you get do not sum up.
>> > On my rather low-end computer (dual core, 3 year old athlon)
> using eSignal as a data source
>> > and 8 charts displayed simultaneously and all visible, the total
> display time is only 0.094 sec
>> > and it is perfectly responsive.
>> >
>> > I guess that this has to do something with the database settings
>> > you are using. Please send screenshots of your File->Database
>> > settings to support.
>> >
>> > Best regards,
>> > Tomasz Janeczko
>> > amibroker.com
>> > ----- Original Message -----
>> > From: "sidhartha70" <sidhartha70@xxx>
>> > To: <amibroker@xxxxxxxxxxxxxxx>
>> > Sent: Friday, December 05, 2008 6:41 PM
>> > Subject: [amibroker] Re: Speed Issues
>> >
>> >
>> >> Addition to this post...
>> >>
>> >> I now have 4 charts opened with a simple price chart displayed
>> >> (Dragged from 'Basic Charts'). Each chart is displayed
> in 'sheet1' of
>> >> the chart. No other 'sheets' contain anything at all. Each
> chart is
>> >> maximised (hence only one visible at a time) and accessable via
> the
>> >> MDI tabs.
>> >> I have 4 intervals displayed... 1 min, 2 min, 3 min and 5 min.
>> >> I use an IQ Feed DB. I'm using 8Gb ram and a 3Ghz octo core
> processor.
>> >>
>> >> Each price chart has a total time of approx 0.0075 secs.
>> >>
>> >> The total redraw time for the four charts together is approx
> 0.45 secs.
>> >>
>> >> Again... this total redraw time seems both very high... and
> makes no
>> >> sense.
>> >>
>> >> Any total chart redraw times of this magnitude seem to make AB
> quite
>> >> unresponsive.
>> >>
>> >> Is anyone actually using AB for live trading using multiple
> charts
>> >> displayed...? If so, please tell me how and what I'm doing
> wrong?
>> >> Because right now, I can't seem to get the requisite speed for
> that to
>> >> be an enjoyable reality.
>> >>
>> >>
>> >> --- In amibroker@xxxxxxxxxxxxxxx, "sidhartha70" <sidhartha70@>
> wrote:
>> >>>
>> >>> Hi All,
>> >>>
>> >>> Just when I think I seem to have got to the bottom of speed
> issues for
>> >>> live trading with AmiBroker... I find myself needing a little
> more
>> >> advice.
>> >>>
>> >>> I have 4 charts... each chart has a total chart timing of
> about 0.045
>> >>> secs.
>> >>>
>> >>> However, the 4 charts in total, have a total redraw time of
> between
>> >>> 0.5 - 0.65 secs.
>> >>>
>> >>> Does this sound reasonable...?? Not quite sure how we get 0.5
> from
>> >>> 0.045 * 4....? If not, any ideas where the extra redraw time
> is coming
>> >>> from...?
>> >>>
>> >>> Second... I'm finding AB, again, very difficult to use for live
>> >>> trading with this kind of redraw speed. What can I do to make
> it
>> >>> faster...?? Any ideas....? (for reference ALL charts have the
>> >>> following line at the end of their code, SetBarsRequired(
> 1000, 200 );)
>> >>>
>> >>> TIA
>> >>>
>> >>
>> >>
>> >>
>> >> ------------------------------------
>> >>
>> >> **** IMPORTANT ****
>> >> This group is for the discussion between users only.
>> >> This is *NOT* technical support channel.
>> >>
>> >> *********************
>> >> TO GET TECHNICAL SUPPORT from AmiBroker please send an e-mail
> directly to
>> >> SUPPORT {at} amibroker.com
>> >> *********************
>> >>
>> >> For NEW RELEASE ANNOUNCEMENTS and other news always check
> DEVLOG:
>> >> http://www.amibroker.com/devlog/
>> >>
>> >> For other support material please check also:
>> >> http://www.amibroker.com/support.html
>> >>
>> >> *********************************
>> >> Yahoo! Groups Links
>> >>
>> >>
>> >>
>> >
>> > ------------------------------------
>> >
>> > **** IMPORTANT ****
>> > This group is for the discussion between users only.
>> > This is *NOT* technical support channel.
>> >
>> > *********************
>> > TO GET TECHNICAL SUPPORT from AmiBroker please send an e-mail
> directly to
>> > SUPPORT {at} amibroker.com
>> > *********************
>> >
>> > For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG:
>> > http://www.amibroker.com/devlog/
>> >
>> > For other support material please check also:
>> > http://www.amibroker.com/support.html
>> >
>> > *********************************
>> > Yahoo! Groups Links
>> >
>> >
>> >
>>
>
>
>
> ------------------------------------
>
> **** IMPORTANT ****
> This group is for the discussion between users only.
> This is *NOT* technical support channel.
>
> *********************
> TO GET TECHNICAL SUPPORT from AmiBroker please send an e-mail directly to
> SUPPORT {at} amibroker.com
> *********************
>
> For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG:
> http://www.amibroker.com/devlog/
>
> For other support material please check also:
> http://www.amibroker.com/support.html
>
> *********************************
> Yahoo! Groups Links
>
>
>
------------------------------------
**** IMPORTANT ****
This group is for the discussion between users only.
This is *NOT* technical support channel.
*********************
TO GET TECHNICAL SUPPORT from AmiBroker please send an e-mail directly to
SUPPORT {at} amibroker.com
*********************
For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG:
http://www.amibroker.com/devlog/
For other support material please check also:
http://www.amibroker.com/support.html
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