Package: dpkg Version: 1.9.20 Severity: normal A profile of 'dpkg-query --status man-db' from CVS (1.9.20 behaves similarly) shows this:
46.43 0.39 0.39 2 195.00 420.00 parsedb 27.38 0.62 0.23 91788 0.00 0.00 findpackage 4.76 0.66 0.04 72859 0.00 0.00 illegal_packagename 3.57 0.69 0.03 47854 0.00 0.00 convert_string real 0m1.848s user 0m1.770s sys 0m0.060s Investigation shows that the hash used to store available packages (lib/database.c) has 128 bins, and was last tuned with a sample set of 141 packages in total. Since there are now over 9000 binary packages in unstable, this could do with being tuned again. Increasing the number of hash bins to 16384 shows a marked improvement: 46.27 0.31 0.31 2 155.00 335.00 parsedb 10.45 0.38 0.07 27891 0.00 0.00 f_filecharf 8.96 0.44 0.06 91788 0.00 0.00 findpackage 8.96 0.50 0.06 19503 0.00 0.01 f_dependency real 0m1.538s user 0m1.410s sys 0m0.110s A patch follows. We haven't tried to see what effect tuning the hash function itself will have yet; it'll probably improve things a little further, but not as much as reducing the enormous number of hash collisions that take place at the moment. --- lib/database.c.orig Mon Mar 25 14:29:00 2002 +++ lib/database.c Mon Mar 25 14:17:02 2002 @@ -26,7 +26,7 @@ #include <dpkg.h> #include <dpkg-db.h> -#define BINS (1 << 7) +#define BINS (1 << 14) /* This must always be a power of two. If you change it * consider changing the per-character hashing factor (currently 5) too. */ Thanks, -- Colin Watson [EMAIL PROTECTED] -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
