Hi, On Sat, Oct 29, 2022 at 2:11 AM Ladislav Lacina <[email protected]> wrote: > > In the last time I worked a lot with the Freepasval compiler. > The computer: Pentium 4, SSD PATA disk, 512MB RAM > The task: Compilation of the full Blocek source ("Build all") - 64603 lines > of code using FreePascal 3.2.0 (GUI) > > FD, cwsdpmi, noUIDE, noLBAcache: 208,2s > FD, cwsdpmi, noUIDE, LBAcache4096: 54,9s > > FD, cwsdpmi, UIDE160, noLBAcache: 72,1s > FD, cwsdpmi, UIDE160, LBAcache4096: 72,2s - 178,8s > > The conclusions: > 1) The speed without any cache is really awfull. On the speed machine and od > the SSD disk! > I do not understand why. Maybe the DOS uses some techniques which are > contraproductive on SSDs
Cache (and even BUFFERS) takes RAM, which early DOS systems couldn't spare. Even MS won't partition larger than 32 GB FAT32 drives because it's slow to access it all in real mode. > 2) Hdpmi32 does not use the RAM disk swapping while CWSDPMI does > and it seems to be a reason why it speeds up the things so much. > I do not understand why CWSDPMI does it even on machine with 512MB RAM. CWSDPMI shouldn't be swapping at all. It does create an empty swap file by default, but it doesn't use it until needed. You are using r7 from 2010, right? CWSDPMI was designed to work on old machines (e.g. his old 386 laptop with only 512 kb of low RAM), so it put the 4 kb page tables in low memory, too. (He said this is also hard to debug / fix.) That will overflow on machines with large amounts of RAM, hence the (default but optional) r7 feature of using Pentium's 4 MB pages when possible. HDPMI32 does presumably keep the page tables in extended memory. If you want to load CWSDPMI resident and try without any swapping, try "cwsdpmi -p -s-". It's still better than Causeway, which will swap the *entire* used RAM out to disk (instead of only how much extra is needed). _______________________________________________ Freedos-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freedos-devel
