On Tue, 2006-04-11 at 18:13, Bart Smaalders wrote: > > There is often an implicit assumption that performance is somehow > a linear function; this is not the case for significant changes. > There are something like 1700 packages in Solaris 11 right now. > Assuming all packages are the same size (or they're installed > randomly), we end up writing 16/2 = 8MB 1700 times, or 13.6 GB > of I/O. This is compared to the 2.7 or so GB that is Solaris > fully installed. Thus removing the repeated writing of the > contents file would reduce the amount of IO needed from about > 16GB to 2.7 GB -> probably worthwhile.
However, this analysis omits 2 important factors: (1) that the quantity of I/O doesn't bear any direct relationship to the time taken to perform it. While the contents file may move more bytes, it takes significantly less time, and (2) that simple modifications to the install process - without modifying pkgadd or the handling of the contents file at all - can reduce the number of bytes needing to be moved by an order of magnitude. Looking at this, my instinct is to say that the problem is not that the contents file is being mishandled, but that the number 1700 is too large. My point is not that the contents file isn't a problem. It is. But it's impact on install times is overstated, and larger gains are to be had elsewhere. -- -Peter Tribble L.I.S., University of Hertfordshire - http://www.herts.ac.uk/ http://www.petertribble.co.uk/ - http://ptribble.blogspot.com/
