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Thanks Tomasz, I will keep that in mind and play around with it a bit
more. I have a quick question about stops though, and I will post it
in a separate thread since it is a new topic.
--- In amibroker@xxxxxxxxxxxxxxx, "Tomasz Janeczko" <amibroker@xxxx>
wrote:
> Hello,
>
> Please keep in mind that AmiBroker keeps in RAM data already loaded
(if possible).
> So if you DECREASE the cache size in the settings and re-run
optimization
> it won't affect your results until you actually restart AmiBroker.
> On the other hand INCREASING cache size should give immediate effect
> as AmiBroker will not need to flush cache.
>
> Another factor is that Windows itself has file-system cache that
causes
> that second reading of the same file may be several times faster
than first access.
> This is so because Windows by itself keeps files in RAM.
> Windows cache mechanism depends on settings in "My computer" as well
> as on amount of memory, system used and if the computer is desktop
or laptop
> (different default settings).
>
> As to your question about besto config.
> Let's calculate how many data you need to cache database in RAM:
> Each data bar: 32 bytes
> # of symbols: 9000
> # of years: 10
> # of bar per year (EOD): 260
>
> = 260 * 10 * 9000 * 32 = 748800000 bytes = 714 MB
>
> So you would need 714 MB of free RAM to have entire 10 year 9000
stock database
> loaded into RAM.
> Plus some additional memory for the system, formula and resutls and
you end up
> with 1GB.
>
> If you don't have that much memory and you are interested in
optimizations mainly
> then it is actually better to shrink AmiBroker cache to minimum
size.
> That way you will reduce swapping.
> This is important because when you set high size for cache it may
happen that
> Windows will need to start swapping and then performance drops
significantly.
>
> All above assumes local database or fast data plugins (Metastock,
FastTrack, QP2)
> If using slower plugins things may look different because time
required to communicate
> with the 3rd party data source may dominate.
>
> Best regards,
> Tomasz Janeczko
> amibroker.com
> ----- Original Message -----
> From: "tycanadian2003" <tyler.schlosser@xxxx>
> To: <amibroker@xxxxxxxxxxxxxxx>
> Sent: Thursday, June 23, 2005 11:21 AM
> Subject: [amibroker] AmiBroker Performance Continued -- What
Settings are Fastest?
>
>
> > Hi again,
> >
> > Thanks for all the responses with respect to my question about
what
> > affects the performance of AmiBroker with regards to computing
> > power. After doing several tests on a few different computers, I
am
> > equally confused about which database settings will offer the
best
> > performance in various situations. Here are some specifics:
> >
> > On an Athlon XP ~2000+ laptop with 512MB RAM, increasing the
maximum
> > RAM allowed under Tools->Preferences->Data seemed to make a
> > noticeable performance difference.
> >
> > On a P4 1.8 GHZ with 1 GB RAM and 10,000RPM SCSI hard drive, any
> > combination of changing max. RAM, bars loaded (this was changed
in
> > the File->Database Settings options since it overrides the one
found
> > in Preferences), and number of symbols to load, seemed to make
very
> > little to no tangible performance difference. On a roughly 8-
minute
> > backtest (run for two iterations in Optimization mode to see if
the
> > second run is any faster than the first due to possibly "loading
it
> > into memory"), any combination of these options was all within 15
> > seconds of all other combinations of options. The same results
were
> > true on the Xeon 3.06 GHZ system with 2 GB RAM.
> >
> > The amount of RAM used by AmiBroker under Task Manager changed a
LOT,
> > but the time it took to finish a two-step optimization changed
only
> > VERY slightly, if at all (this could be attributed to the
differences
> > in myself opening and closing the task manager window, etc.).
> >
> >
> > My question is: What are the best settings to use for a locally
> > stored (C:) database with about 9,000 symbols for 10 years of EOD
> > data? Since I assume the PC specs matter, what are the best
settings
> > to use for a PC with essentially unlimited RAM vs. one with only
> > 512MB vs. 1 GB of RAM?
> >
> > If anyone could offer some guidance (Tomasz?), or possibly
explain
> > these results, I would appreciate it greatly.
> >
> > P.S. I agree that Athlons are probably best as well, my PC at
home
> > is an Athlon and seemed to perform very well, but sadly I am
across
> > the world right now (Switzerland) and just stealing a bunch of
> > computers here at work (which are all IBM Intel-based) to run my
> > AmiBroker stuff. So that's all I have to benchmark,
unfortunately.
> >
> >
> >
> >
> > Please note that this group is for discussion between users only.
> >
> > To get support from AmiBroker please send an e-mail directly to
> > SUPPORT {at} amibroker.com
> >
> > For other support material please check also:
> > http://www.amibroker.com/support.html
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
Please note that this group is for discussion between users only.
To get support from AmiBroker please send an e-mail directly to
SUPPORT {at} amibroker.com
For other support material please check also:
http://www.amibroker.com/support.html
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