Hi all, I would like to comment on the new QDMA cache feature, after Johnson gave me some background information...
On Mon, 3 Jul 2006, Johnson Lam wrote: > visit my homepage (http://johnson.tmfc.net) and have a look. > > The latest driver not only do UltraDMA, also can REPLACE the bulky > SMARTDRV, NORTON CACHE and CACHE2 ... with 3K resident size (oh, > benchmark welcome, it's a read cache), performance should be close to > them or better. The feature does replace CACHE2, but it does not replace more advanced caches like MS DOS SMARTDRV or DR DOS NWCACHE and similar. The good thing with QDMA caching is that it only takes less than 2k of DOS RAM and more or less no extra XMS, because it shares buffers with XMS buffers which QDMA already had before. What you get are 64k (128 sectors) of extra BUFFERS, roughly speaking. Only single sector access is cached, not access which reads larger chunks. This is useful because the cache is small and would only be "overwhelmed" by caching large files. This again makes it similar to BUFFERS. There is no delayed / pooled write caching either, but remember that QDMA has WRITE OVERLAP which means the software returns to the caller after telling the hardware to handle the write, so you only have to wait for the disk when a previous write is still in progress at the moment when you want to do the next disk access. In short, a nice extra for people who want to use little XMS and little DOS memory but still want to have a cache. Note that disks are so fast today that caching a fast disk on a slow PC can make overall speed actually go down, especially if you use a large cache configured to a "think a lot about caching strategy" mode. However, having a large cache is always a good idea if you want to reduce noise or want to reduce energy consumption :-). And, in DOS, also if you have nothing better to do with your modern gigabytes of RAM ;-). Eric Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Freedos-user mailing list Freedos-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-user
