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TJ: I am merely suggesting that some work could be shifted from once
per optimization step to once per optimization run and that many of
your customers would benefit.
If you don't like the suggestion, fine. But there is no reason to be
a jerk about it.
--- In amibroker@xxxxxxxxxxxxxxx, "Tomasz Janeczko" <groups@xxx>
wrote:
>
> Hello,
>
> Of course AFL execution is just a FRACTION of time needed to
> perform full-featured portfolio backtest. There are many other steps
> involved, namely:
>
> PHASE 1:
> FOR EVERY SYMBOL UNDER TEST
>
> A) preparing data
> This involves the following sub steps:
> a.1) reading the data from the disk (if not cached already) or
requesting data from external plugin (many external sources are
> pretty slow)
> a.2) time compressing in selected periodicty (say your database is
1-minute
> and your optimization periodicity is 5 minute)
> a.3) filtering for weekends/regular trading hours etc (if enabled)
> a.4) performing padding to reference symbol (if enabled)
> Note that steps a.2 and a.3 are done simultaneously (in one loop)
for speed
>
> B) AFL execution (that is what is reported as "AFL execution time").
>
> b.1) setting up AFL engine - allocating and filling built in arrays
(buyprice/sellprice/shortprice/coverprice/margindeposit/
> positionsize/open/high/low/close/openint/volume, etc....)
> b.2) actual execution
> b.3) cleanup (freeing allocated temporary memory used for execution)
>
> C) collection / sorting / ranking of trading signals
> After buy/sell/short/cover arrays are known AmiBroker collects
signals
> and ranks them according to position score. At this step also
> features like HoldMinBars, trading delays, various kinds of
> built-in stops, etc, etc.
>
>
> PHASE 2:
> ONCE FOR BACKTEST (or OPTIMIZATION STEP):
> D.1) Actual Porftfolio backtest (simplified a bit):
>
> For EVERY BAR under test
> {
> For EVERY SIGNAL in the sorted signal list
> {
> PROCESS SIGNAL (signal processing is complex as it handles
features like multiple currencies and scaling, early exit penalty
> fees)
> UpdateEquity()
> }
> Calculate TRADE STATISTICS
> Calculate EQUITY STATISTICS
> Evaluate/Handle STOPS
> }
>
> Note that if any Custom Backtester procedure is defined there is
one more AFL execution
> that allows to control D.1.
>
> D.2) Report output (generating HTML backtest report), generating
MAE/MFE charts
>
> All those non-afl-execution steps, account for roughly 1-2
nanoseconds overhead per bar per symbol.
>
> I would not say that 1-2 nanosecond overhead is "not-efficient"
or "performance bottleneck"
> considering the amount of work fully featured portfolio backtester
is doing.
>
> If you do the math.
> 10 step optimization * 850 symbols * 20000 bars per symbol gives
>
>
======================================================================
============
> You got 170 MILLION (1.7e8) bars to process. Multiply that by 1
nanosecond (1e-9) and you will get 17 seconds.
>
======================================================================
============
>
> Quite frankly it seems that you are comparing apples to oranges. If
your own codes simply do not do steps
> A) C) and D) it surely will run faster but any code that does less
work will run faster.
> I am not sure what is the purpose of this thread. I am getting
pretty tired trying to convince you
> that I did my job well.
>
> Best regards,
> Tomasz Janeczko
> amibroker.com
> ----- Original Message -----
> From: "dloyer123" <dloyer123@xxx>
> To: <amibroker@xxxxxxxxxxxxxxx>
> Sent: Wednesday, August 13, 2008 3:03 AM
> Subject: [amibroker] Re: Freakishly fast backtest using 64 cores
>
>
> > The idea of using array processing for this problem rather than
the
> > more traditional for/next loop was a really good idea. That part
of
> > the system is very fast at what it does and provides a great
amount
> > of freedom and flexibility.
> >
> > However, consider the trivial system:
> >
> > Buy = 0;
> > Sell = 0;
> > Short = 0;
> > Cover = 0;
> > Optimize("val",0,1,10,1);
> >
> > Clearly the AFL engine is being invoked, but this could be
considered
> > the fastest possible AFL code, or very close to it. It's
execution
> > time is not zero, but pretty darn close. The "check alf" function
> > measures 0.3ms for 64,000 bars, for the "Optimize" statement.
> >
> > On my 3Gz Core 2, this system takes 18 seconds to backtest over a
> > portfolio of 850 symbols, 1 year, 5 minute bars. This time does
not
> > vary much with the size of the test window. Since "Quick AFL" is
> > slected, there should be about 20k bars per symbol.
> >
> > Running optimize, takes roughly the same time as the backtest for
> > each and every pass, 18 seconds each and every time. That 18
seconds
> > can not be explained by the AFL code execution alone. There is
other
> > stuff being done that takes much, much, much longer.
> >
> > So, even if AFL execution runs in zero time, this is the limit of
how
> > fast AmiBroker can optimize.
> >
> > So, yes, the AFL execution is highly optimized and very fast, but
> > there is a lot of overhead that is outside of the AFL execution.
I
> > could guess what it is doing, but it really does not matter.
> >
> > I am only pointing out that it a very juicy opportunity for
> > meaningful performance gains.
> >
> > Yes, there are memory management issues, and yes, some data sets
may
> > be too large to take advantage of it, but a large fraction of your
> > customer base would. It could even be made transparent to the
user
> > with no extra checkboxes. No exotic hardware required. It would
> > even work on a laptop.
> >
> > When I run my system on the emulator, it just runs on the normal
cpu
> > core, using normal system memory. If anything, there has to be a
lot
> > of overhead in pretending to run as so many threads, and the data
set
> > is far larger than the L2 cache. But it is still much faster than
> > the built in backtest. Yes, part of that is hand optimized code,
but
> > that does not explain the performance differential or 20x to 50x
of
> > Ami vs emulator. Running on the GPU is more like 4000x. Yes the
> > GPU, has more memory bandwidth to work with, but not that much
more.
> >
> > I would say that the AFL execution code is highly optimized and
fully
> > exploits the hardware it has to work with, but that there are
> > performance bottlenecks elsewhere in the critical path. I can not
> > tell you what they are, but I would guess that it is rebuilding
price
> > arrays and maybe other data structures on every pass.
> >
> > Anyway, I dont mean to tell you your business and you are much
closer
> > to this problem than I am. Maybe there is some edge case that I
have
> > not considered that forces a performance hit. It is still way
faster
> > than EasyLanguage.
> >
> > I am a big fan of your work and enjoy using your product. The
> > passion that you put into it shows.
> >
> >
> >
> > --- In amibroker@xxxxxxxxxxxxxxx, "Tomasz Janeczko" <groups@>
> > wrote:
> >>
> >> Hello,
> >>
> >> What is true for GPU it is not necesarily true for CPU. GPU has
> > dedicated wide RAM
> >> bus and faster RAM as opposed to system memory.
> >>
> >> AmiBroker does a lot to utilise memory to maximum extent where
> > possible/feasible.
> >>
> >> Actually AFL speed is limited by system memory if you run out of
on-
> > chip cache.
> >> http://www.amibroker.com/kb/2008/08/12/afl-execution-speed/
> >>
> >> So going for more memory usage not always means faster execution.
> >>
> >> Sure you can pre-compute everything, and use pre-computed values
> > but
> >> you need to understand that people are doing VERY different
things
> > with AmiBroker
> >> and their problems are not the same as problems you are trying to
> > solve.
> >> For example some customers are backtesting entire US stock
universe
> > (8000+ symbols)
> >> over 10 or 20 years. That's about 1.3GB for DATA alone. Now if
you
> > are running
> >> porfolio backtest you need to keep trading signals and that can
be
> > as much as 1GB in
> >> such case. Quickly you are reaching 3GB RAM limit of 32 OS. There
> > is no place
> >> to store "pre-computed" values.
> >> AmiBroker by nature needs to provide best blend of speed,
moderate
> > memory / CPU requirements.
> >> User-specific single-task solutions may go into specialisation
and
> > tricks that are
> >> not feasible for commercial general-purpose product that is
> > intended to keep
> >> large user base happy.
> >>
> >> Best regards,
> >> Tomasz Janeczko
> >> amibroker.com
> >> ----- Original Message -----
> >> From: "dloyer123" <dloyer123@>
> >> To: <amibroker@xxxxxxxxxxxxxxx>
> >> Sent: Tuesday, August 12, 2008 4:09 PM
> >> Subject: [amibroker] Re: Freakishly fast backtest using 64 cores
> >>
> >>
> >> > The programing guide lists the 8600M and 8700M as having 32
> > computing
> >> > cores. Not sure what they are clocked at. Power is an issue.
> > The
> >> > desktop versions need dedicated power connectors. The big
cards
> > need
> >> > two.
> >> >
> >> > Actually, when I am doing development on my laptop, I just use
> > the
> >> > emulator. It is about 100x slower than my desktop system, but
> > still
> >> > about 20x to 50x faster than Ami alone. The speed difference
in
> >> > emulation mode is mostly due to the precomputed and cached
price
> >> > arrays.
> >> >
> >> > Tomasz: I suspect that there is an opportunity to trade memory
> > for
> >> > speed, even with 1 core. Memory is cheap and would be a
simpler
> > way
> >> > to get a performance boost than porting to multi core, GPU or
> > CPU.
> >> >
> >> >
> >> >
> >> > --- In amibroker@xxxxxxxxxxxxxxx, "Tomasz Janeczko" <groups@>
> >> > wrote:
> >> >>
> >> >> Dell has 3 off the shelf
> >> >> > laptops in their entertainment/performance range that use
> > GeForce
> >> >> > 8600M and 8700M with 256MB & 2*2456MB (min 256 required for
> > CUDA?)
> >> >>
> >> >> Mobile ones are very poor cousins. Belive me. I own brand new
> >> > notebook (ASUS) with GeForce8600M
> >> >> and it is SLOW in 3D. I mean SLOW. Did I mention that it is
> > SLOW?
> >> >>
> >> >> In 3D Mark it gets the same results as my 3 year old desktop
> > 6600GT.
> >> >>
> >> >> Best regards,
> >> >> Tomasz Janeczko
> >> >> amibroker.com
> >> >> ----- Original Message -----
> >> >> From: "brian_z111" <brian_z111@>
> >> >> To: <amibroker@xxxxxxxxxxxxxxx>
> >> >> Sent: Tuesday, August 12, 2008 12:40 AM
> >> >> Subject: [amibroker] Re: Freakishly fast backtest using 64
cores
> >> >>
> >> >>
> >> >> > DL
> >> >> >
> >> >> >
> >> >> > I am following at the top level and understand what you are
> > doing
> >> > OK
> >> >> > (you make me wish I had learnt programming/IT).
> >> >> >
> >> >> > I like your CPU.
> >> >> >
> >> >> > Allowing niche trading is what AB is all about?
> >> >> >
> >> >> > I'll put my money on MS/"general purpose computing on GPU" -
I
> >> > don't
> >> >> > think the masses are in love with MS but for 80% of people
who
> >> > can do
> >> >> > 80% of what they want with MS the price to move elsewhere is
> > too
> >> >> > high - they are just in love with max output for min input.
> >> >> >
> >> >> > If you go to the trouble to write a plug-in do you think it
> > will
> >> > be
> >> >> > around long/require much ongoing support from you?
> >> >> >
> >> >> > I can see the benefits of the speed - for a group of traders
> > it
> >> > is a
> >> >> > definite edge they would have for a year or two (I don't
think
> >> > any
> >> >> > other trading software will be seeing this for a while? -
> >> > especially
> >> >> > in the AT area where more crunching could be done fast
enough
> > to
> >> > keep
> >> >> > up with live data.
> >> >> >
> >> >> > I don't blame Tomasz for not sitting his backside on the
> > cutting
> >> >> > edge - too dangerous for developers with long term
clientele.
> >> >> >
> >> >> > Not having a go at Tomasz - to clarify - Tomeasz said
GEForce
> >> > 8800
> >> >> > can't be put in a notebook?
> >> >> >
> >> >> > To my understanding there seems to be a reasonable number of
> >> > laptops
> >> >> > around that could use your method e.g. Dell has 3 off the
> > shelf
> >> >> > laptops in their entertainment/performance range that use
> > GeForce
> >> >> > 8600M and 8700M with 256MB & 2*2456MB (min 256 required for
> > CUDA?)
> >> >> >
> >> >> > I looked at the GeF links in Paul's post but they didn't
have
> >> > much
> >> >> > specific info there that I could see - I assume the above
> > cards
> >> > wiil
> >> >> > run your system.
> >> >> >
> >> >> > I am not a buyer for now but good luck with it and what you
> > have
> >> > done
> >> >> > already is a good contribution to AB - once someone on the
> > block
> >> > has
> >> >> > a new super-dooper gadget pretty soon the neighbours want
one
> > too
> >> > and
> >> >> > demand grows.
> >> >> >
> >> >> > brian_z
> >> >> >
> >> >> >
> >> >> >
> >> >> > --- In amibroker@xxxxxxxxxxxxxxx, "dloyer123" <dloyer123@>
> > wrote:
> >> >> >>
> >> >> >> This uses the mid range video card that happened to come
with
> > my
> >> >> >> system, a 9800GT. The newer 260 and 280 cards are 3 to 4
> > times
> >> >> >> faster. The 260 can be found at best buy for $300. Some
> >> > laptops
> >> >> >> have compatible cards as well.
> >> >> >>
> >> >> >> The video card has its own memory, mine has 512MB, some
have
> > as
> >> >> > much
> >> >> >> as 1GB. This memory is very fast, once it is loaded from
the
> >> > main
> >> >> >> system. Nvidia has a professional line of products that
have
> >> > much
> >> >> >> more memory.
> >> >> >>
> >> >> >> Get get the best performance, my AFL code makes one pass
over
> >> > the
> >> >> >> data, calling a Dll. The Dll takes all of the data needed
by
> >> > the
> >> >> >> calculation and loads a copy to the video card. This
upload
> > is
> >> >> > slow,
> >> >> >> the entire upload takes about 45 seconds for all 1000
> > symbols.
> >> >> >>
> >> >> >> Once all of the data is uploaded, the Dll loads a "kernel"
> > into
> >> > the
> >> >> >> graphics cores that perform the actual computation and
> > generates
> >> >> > the
> >> >> >> trade list. This part is very fast and performs all of the
> > same
> >> >> >> functions that my AFL version does. The resulting trade
list
> > is
> >> >> > the
> >> >> >> same.
> >> >> >>
> >> >> >> Because the data loaded into video memory, it can be
resused
> > for
> >> >> > many
> >> >> >> passes over the data with different optimization values.
So,
> >> >> >> hundreds of combinations of optimization values can be
tried
> > per
> >> >> >> second.
> >> >> >>
> >> >> >> For non optimization runs, the Dll just loads one symbol
into
> >> > video
> >> >> >> memory and processes it. Counting the overhead of moving
> > data
> >> > to
> >> >> > the
> >> >> >> video card and extracting the trade list for a single
symbol,
> >> > the
> >> >> >> result is similar to AFL code alone. This lets me test the
> > code
> >> >> > and
> >> >> >> make sure it is correct.
> >> >> >>
> >> >> >> This approach works best when the data only needs to be
> > loaded
> >> >> > once,
> >> >> >> then "resused" many times. It also works best when there
is
> > a
> >> > lot
> >> >> > of
> >> >> >> data to work with.
> >> >> >>
> >> >> >> What is more interesting to me and what would be more
useful
> > for
> >> >> >> others would be a general drive that requires no Dll
changes
> > to
> >> >> >> modify the system. The performance would not be as good as
> > hand
> >> >> >> optimized code, but would still be much better than AFL
code
> >> >> > alone.
> >> >> >> It would take trading system design to a whole new level.
It
> >> > would
> >> >> >> provide enough performance to make working with Intra day
> > data
> >> > as
> >> >> >> easy as daily data is today.
> >> >> >>
> >> >> >> Writing such a driver would be hard, but I have already
done
> >> > some
> >> >> >> prototypes and design work. I am tempted to do it for my
own
> >> > use.
> >> >> >> If I made it available to others supporting it would be a
> > PITA.
> >> >> >>
> >> >> >>
> >> >> >>
> >> >> >>
> >> >> >> --- In amibroker@xxxxxxxxxxxxxxx, "Paul Ho" <paul.tsho@>
> > wrote:
> >> >> >> >
> >> >> >> > I'm very interested
> >> >> >> > could you elaborate a bit more
> >> >> >> > What model of Nvidia chipset are you using, and with how
> > much
> >> >> >> memory?
> >> >> >> > Not sure exactly what you mean when you say
> >> >> >> > It uses AmiBroker to load the symbol data and perform
> >> >> > calculations
> >> >> >> > that do not depend on the optimization parameters. Once
> > loaded
> >> >> > into
> >> >> >> > video memory, repeated passes can be made with different
> >> >> >> parameters,
> >> >> >> > avoiding any overhead.
> >> >> >> > Can you give me some examples. I presume when your dll is
> >> > called.
> >> >> >> AB passes
> >> >> >> > one or more arrays of data belonging to 1 symbol, is that
> > true?
> >> >> >> > Not sure exactly what the rest mean either. How many
> > functions
> >> >> > are
> >> >> >> you
> >> >> >> > running in your dll, and what does each of the do?
> >> >> >> > Great of you to share your insight.
> >> >> >> > Cheers
> >> >> >> > Paul.
> >> >> >> >
> >> >> >> >
> >> >> >> >
> >> >> >> > _____
> >> >> >> >
> >> >> >> > From: amibroker@xxxxxxxxxxxxxxx
> >> >> > [mailto:amibroker@xxxxxxxxxxxxxxx]
> >> >> >> On Behalf
> >> >> >> > Of dloyer123
> >> >> >> > Sent: Tuesday, 5 August 2008 9:19 AM
> >> >> >> > To: amibroker@xxxxxxxxxxxxxxx
> >> >> >> > Subject: [amibroker] Freakishly fast backtest using 64
cores
> >> >> >> >
> >> >> >> >
> >> >> >> >
> >> >> >> > Greetings,
> >> >> >> >
> >> >> >> > I ported part of my AFL backtest code to a plugin, that
> > takes
> >> >> >> > advantage of the graphics math cores on the video card
that
> >> > are
> >> >> >> > normally used for 3d graphics.
> >> >> >> >
> >> >> >> > I was able to get a several thousand fold performance
> >> > improvement
> >> >> >> > over AFL code alone.
> >> >> >> >
> >> >> >> > My goal was to reduce the 25 seconds AFL code alone uses
> > for a
> >> >> >> single
> >> >> >> > portfolio level back test to less than 1 second, allowing
> >> > multi
> >> >> > day
> >> >> >> > optimization and walkforward runs to complete in a more
> >> >> > reasonable
> >> >> >> > time, and also just to see how fast I could get it to
run.
> >> >> >> >
> >> >> >> > The backtest runs over 1 year of 5 minute bars for about
> > 1000
> >> >> >> > symbols. 1 year of data normally takes 25 seconds for
> >> > AmiBroker
> >> >> >> > alone, or 18 seconds for 6 months of data. A typical
> >> > optimization
> >> >> >> > run takes hundreds of these passes per walk forward step,
> >> > taking
> >> >> >> > hours.
> >> >> >> >
> >> >> >> > Using the Nvidia CUDA API, running on my mid range video
> > card.
> >> > It
> >> >> >> > was much faster. Much, much, much faster. How fast?
> >> >> >> >
> >> >> >> > It reduced the run time from 25s to... 4.4ms. That is
more
> >> > than
> >> >> >> > 200/s!
> >> >> >> >
> >> >> >> > I didnt believe the timing when I saw it at first. So, I
> > put
> >> >> > 1,000
> >> >> >> > runs in a loop and sure enough, it ran 1,000 iterations
in
> >> > about
> >> >> > 4
> >> >> >> > 1/2 seconds. This far exceeded my gaol or expectations.
> >> >> >> >
> >> >> >> > The resulting trade list matches that obtained by the AFL
> >> > version
> >> >> >> of
> >> >> >> > this code.
> >> >> >> >
> >> >> >> > I estimate that it is processing 32GB of bar data/sec.
> >> >> >> >
> >> >> >> > Getting this to work at peak performance was tricky. Most
> > of
> >> > what
> >> >> > I
> >> >> >> > have learned about code optimization does not apply.
> >> >> >> >
> >> >> >> > It uses AmiBroker to load the symbol data and perform
> >> >> > calculations
> >> >> >> > that do not depend on the optimization parameters. Once
> > loaded
> >> >> > into
> >> >> >> > video memory, repeated passes can be made with different
> >> >> >> parameters,
> >> >> >> > avoiding any overhead.
> >> >> >> >
> >> >> >> > For non backtest/optimization runs, the code just
evaluates
> >> > one
> >> >> >> > symbol and passes the data back to AmiBroker
> >> > buy/sell/short/cover
> >> >> >> > arrays, making it easy to test, validate and visualize
the
> >> >> > trades.
> >> >> >> > There is very little performance gain in this case.
> >> >> >> >
> >> >> >> > There are problems, however. To run optimizations at peak
> >> > speed,
> >> >> > I
> >> >> >> > can not use AmiBroker to calculate the optimization goal
> >> >> > function.
> >> >> >> > So, I am in the process of writing code to match signals
> > and
> >> >> >> > calculate the portfolio fitness function. Once I do
this, I
> >> > will
> >> >> > be
> >> >> >> > able to perform full optimizations and walk forwards at 3
> >> > orders
> >> >> > of
> >> >> >> > magnitude faster than is possible with AmiBroker alone.
> >> >> >> >
> >> >> >> > Also, this is not general purpose code. Changing the
system
> >> > code
> >> >> >> > means changing a dll written in C. However, there is no
> > reason
> >> >> > that
> >> >> >> > this could not be made more general.
> >> >> >> >
> >> >> >> > I have made some prototypes of "Cuda" versions of basic
AFL
> >> >> >> > functions. The idea is to queue the function calls into a
> >> >> >> definition
> >> >> >> > executed by a micro kernel running on the graphics cores.
> > The
> >> >> >> result
> >> >> >> > would be the ability to use the full power of the
graphics
> >> > cores
> >> >> > by
> >> >> >> > modifying AFL code to use Cuda aware versions with no
> > changes
> >> > to
> >> >> > C
> >> >> >> > code. It would be an interesting, but big project.
> >> >> >> >
> >> >> >>
> >> >> >
> >> >> >
> >> >> >
> >> >> > ------------------------------------
> >> >> >
> >> >> > 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 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
> >> >> >
> >> >> >
> >> >> >
> >> >>
> >> >
> >> >
> >> >
> >> > ------------------------------------
> >> >
> >> > 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 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
> >> >
> >> >
> >> >
> >>
> >
> >
> >
> > ------------------------------------
> >
> > 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 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
> >
> >
> >
>
------------------------------------
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