RE: And the Winner Is.../faster stll?

["Albertson, Chris" <CAlbertson@primeadvantage.com>]

Rob,

Email me and I'll send you a little snippet of code that
reads out the RAM buffer in about 8 seconds.  If you are
reading out the card with a byte wide read infor a "for
loo" this will go about 5x faster.  If you are already
reading by the same method I use then it is just that
Windows is dog slow.  My P100 beats Tom's K500 by about
a factor of five.

My P100 with Mk IV electronics is aailable on-line 24x7.
Just ask if you want access.  This is a Mk IV system that
is intended for public access.  The control computer runs
_both_ MS DOS 6.2 and QBASIC and RedHat Linux 6.2 (Wow the
same versions.) 

> -----Original Message-----
> From: Tom Droege [mailto:tdroege@veriomail.com]
> Sent: Monday, February 05, 2001 10:51 AM
> To: tass@listserv.wwa.com
> Subject: And the Winner Is...
> 
> 
> Rob now has his code working so we can compare the results:
> 
> Tom        QuickBasic       64.48 Seconds
> Rob         C and CFITSIO  37.12 Seconds
> Andrew   Pascal                35.12 Seconds
> 
> All tests were made on a 500 MHz K6 in a DOS window with no 
> other windows 
> open.  It is also run with an ALT ENTER which gives windows the full 
> screen.  This may make a difference.  Note that the programs 
> slow down a 
> lot, as much as a factor of two, if a second window is open.
> 
> Tom is not writing a .fts header so the raw files need a 
> processing step 
> with RawToFits with will take a few seconds per file.  Note 
> that this only 
> takes a few seconds, so it is much faster to read a file, add 
> a .fts header 
> and then write it back to disk than it is to read from the 
> memory card and 
> write a disk file.  Obviously most of the time is taken 
> reading the memory 
> card with an 8 bit wide I/O instruction.
> 
> Rob is using C and CFITSIO which wirtes out an "official" 
> looking .fts 
> header.  He is also writing out some test data so it is 
> possible that the 
> program will speed up a little when that is removed.
> 
> Andrew is coding in Pascal and makes up his own .fts header.
> 
> It looks like we are running up against the brick wall of the 
> I/O speed.  I 
> am curious as to how Chris gets to 20 seconds.
> 
> OK, this is just great and a near halving of the present run 
> time with 
> QBasic.  It also writes out the .fts headers on the first pass.  The 
> remaining job is to have the program read in two files that I 
> will write in 
> a specified format to put arbitrary things into the .fts header.  I 
> envision a constants file which contains things like location name, 
> lattitude and longitude, etc..  The second file will be 
> changed each time 
> the program runs and writes a file and will include things 
> like shutter 
> open times and RA and Declination of the telescope.  OK, you 
> experts will 
> have better names for these files, I will fix my QBasic code to write 
> anything requested.  I hope I can write straight .txt files.
> 
> Thanks to everyone who has worked on this so far.  This will 
> help a lot.
> 
> Tom Droege
> 
>