Hi, I maintain a system that is used to hold a rather large CVS repository (~1GB give or take) which could do with being faster. Tagging in particular is slow and I don't think cpu or ram is the issue (it is a dual xeon with 3GB of RAM).
My suspicion is that at least one of the problems is that when a tag is added most of the rcs files are rewritten giving a sudden large amount of data that must be written to disc. So - here are my questions/ideas - I'd appreciate comments to tell me whether I'm on the right lines: 1) As I understand it the tag data is the first of the 3 main data structures in the RCS file (tag, comments, diffs) and that when I do pretty much any CVS operation I rewrite the whole file - is this correct? 2) White space appears to be irrelevent in RCS files; so adding arbitrary amounts in between sections should leave files still fully compatible with existing RCS/cvs tools. 3) So the idea is that when I add a tag I add a bunch of white space after the tag (lets say 1KB of spaces split into 64 byte lines or similar); when I come to add the next tag I check if there is plenty of white space, if there is then instead of rewriting the file I just overwrite the white space with my new tag data; if there is no space then as I rewrite the file I add another lump of white space. 4) Whether dummy white space is added and how much is controlled by the existing size of the RCS file; so an RCS file that is only a few KB wont have any space added; that way this mechanism doesn't slow down/bloat small repositories. The amount of white space might be chosen to align data structures with disk block boundaries. 5) My main concern is to do with concurrency/consistency requirements; is the file rewrite essential to ensure consistency, or is the locking that is carried out sufficient? Does this make sense? Dave -----Open up your eyes, open up your mind, open up your code ------- / Dr. David Alan Gilbert | Running GNU/Linux on Alpha,68K| Happy \ \ gro.gilbert @ treblig.org | MIPS,x86,ARM,SPARC,PPC & HPPA | In Hex / \ _________________________|_____ http://www.treblig.org |_______/ _______________________________________________ Info-cvs mailing list Info-cvs@gnu.org http://lists.gnu.org/mailman/listinfo/info-cvs
