Once again, we have put some effort into associating patches with the companies that supported this work, with the results shown below. These results should always be taken as approximations; we believe that they are essentially correct, but patches do not come with Paid-for-by: headers, so a certain amount of guessing is always required.

Top ten most active 2.6.23 employers by changesets

• (Unknown) (1180, 19.0%)
• Red Hat (744, 12.0%)
• (None) (559, 9.0%)
• IBM (507, 8.2%)
• Novell (421, 6.8%)
• Intel (184, 3.0%)
• Oracle (146, 2.4%)
• Renesas Technology (134, 2.2%)
• MIPS Technologies (119, 1.9%)
• NetApp (116, 1.9%)

Top ten most active 2.6.23 employers by lines changed

• (Unknown) (111777, 16.9%)
• (None) (99649, 15.0%)
• Red Hat (84224, 12.7%)
• IBM (39449, 5.9%)
• Oracle (36205, 5.5%)
• Renesas Technology (33152, 5.0%)
• HP (18718, 2.8%)
• Tripeaks (18567, 2.8%)
• Novell (17990, 2.7%)
• Emulex (15942, 2.4%)

Red Hat retains its place at the top of the by-changesets list, though its percentage of changes has dropped a bit. By lines changed, developers known to be working on their own time (the "None" entry) beat out all corporate contributors. It is worth noting that much of lines-changed count for those developers is, in fact, lines removed.

Looking at who added Signed-off-by: lines to patches is interesting, especially if one looks at signoffs added by people other than the author of the patch. In this way, one gets an idea of who the gatekeepers are. There is a slight change to how this calculation was done this time around: if a patch carried signoffs from both Linus Torvalds and Andrew Morton, Linus's was not counted. As a result of how the process works, everything that goes through Andrew gets a signoff from Linus; not counting those signoffs gives a more accurate picture of how the review was actually done.

Top Ten developers with the most signoffs (total 5653)

• Andrew Morton (1247, 21.6%)
• Linus Torvalds (397, 6.9%)
• David S. Miller (381, 6.6%)
• Greg Kroah-Hartman (329, 5.7%)
• Jeff Garzik (287, 5.0%)
• James Bottomley (264, 4.6%)
• Paul Mackerras (223, 3.9%)
• Mauro Carvalho Chehab (150, 2.6%)
• Len Brown (128, 2.2%)
• Ralf Baechle (122, 2.1%)

One question which comes up sometimes is: how do these numbers look for specific parts of the kernel tree? The author duly hacked on his scripts to generate this sort of information. Here is a summary of the results - using the employer by-changesets numbers: