From: "Matthias Paul" Organization: Rechenzentrum RWTH Aachen To: opendos AT delorie DOT com Date: Tue, 23 May 2000 15:09:56 +0100 Subject: Re: Optimising disk access in DRDOS X-mailer: Pegasus Mail v3.22 Message-ID: <3740AD74FBA@reze-1.rz.rwth-aachen.de> Reply-To: opendos AT delorie DOT com On 13 May 00 09:21:57 Joseph Morris wrote: > > - Try DEBLOCK=FFFF in CONFIG.SYS. This also speeds up things > > (if it is not the default already - which is detected on > > startup), but it may make your system unstable if you are > > using old SCSI or ESDI drivers for harddisks (pre Virtual > > DMA Specification (VDS) 1.0). However, I have yet to see > > a system where it actually caused problems. > > Isn't VDS for V86 mode? I'm not running EMM386 because it doesn't > support VESA VBE 2.0 which I'm using in the program. Most probably it's at FFFF already due to the automatic detection in the kernel. However, it shouldn't harm to explicitely set it to DEBLOCK=FFFF in CONFIG.SYS - just in case... > > As already mentioned, a RAMdisks is also a good solution. > > But they're volatile. I'm developing a program, and the cycle I'm using > is like: > > run program > change datafiles > run program > change datafiles > .... > > By keeping the data on a VDISK I run the risk of losing the data > I'm trying to perfect by forgetting to copy it back. Also the program > may crash (although this is very rare nowadays). I see. However, you mentioned that the program accesses the files very frequently. Hence it might still be an option to try the following: copy from HDD to RAM disk run program on RAM disk copy back from RAM disk to HDD change datafiles copy from HDD to RAM disk run program on RAM disk ... Depending on what the program actually does (and how much of it can be catched by NWCACHE), this might still be faster than permanently working on HDD. > > > Having seen how fluidly the my program runs when compiled for Linux, > > > or even the DOS version run in Windows 95, I'm a bit concerned > > > about how slow it is running under DRDOS. > > Have you tried it under pure MS-DOS, or from within the GUI? > > Inside the GUI. I did wonder if this is a result of the 32 bit hooks > into the DOS VM. I think it's a result of the better caching methods and available when Vcache is active (that is, you're inside of the GUI). It would be interesting to see, if under plain vanilla DOS (given the same or similar configuration), DR-DOS would still be much slower than MS-DOS. However, I don't see other methods how to speed up things then (except for improving the kernel and/or NWCACHE). However, personally I'm quite happy with NWCACHE's performance. Matthias ------------------------------------------------------------------- Matthias Paul, Ubierstrasse 28, D-50321 Bruehl, Germany eMail: Web : http://www.rhrz.uni-bonn.de/~uzs180/mpdokeng.html -------------------------------------------------------------------