While Torvalds normally does the new kernel releases on Sundays, he decided to tag 4.3-rc1 a day short and close the merge window early to surprise those that may have been holding off on their pull requests for Linux 4.3 until the last day.
About Linux 4.3, Linus wrote in the announcement:
I had expected 4.3 to be somewhat smaller after that pretty big 4.2, but it's not particularly small - pretty average in size, in fact. Everything looks fairly normal, in fact, with about 70% of the changes being drivers, 10% architecture updates, and the remaining 20% are spread out (filesystems, networking, tooling, documentation, mm and "core" kernel updates etc).I've already written dozens of news articles about changes for Linux 4.3. I'll try to write my usual article on Sunday about the Linux 4.3 kernel features; pardon for the light news so far this weekend due to having been hospitalized and needing fifteen stitches to my foot, still recovering... Some of the Phoronix articles already have included Linux 4.3 kernel benchmarks while I'll be running many more in the days/weeks ahead. There's also the daily Linux kernel Git benchmarking done over at LinuxBenchmarking.com.
On the driver side, the GPU drivers remain a noticeable chunk, partly because of the Nouveau updates that missed 4.2, so there's effectively two releases worth of updates there. But there's driver updates to pretty much all the other driver subsystems too. So there's networking drivers (wired and wireless), staging, media, crypto, pinctrl, you name it.
The architecture updates are about half arm (devicetree updates are noticeable), with half being spread out (x86, mips, arm64, powerpc, s390).
On the filesystem side, the bulk of the changes (in lines of code) is the removal of the ext3 filesystem (with ext4 remaining to support ext3 layouts - but the separate ext3 codebase is gone). But there are misc updates all over: f2fs, btrfs, nfs, xfs, ufs, gfs2, proc...