[Google Pixel 3 XL ROMs, Kernels, Recoveries, & Oth] Freak07:
Update to 2.0.8

Hey guys and girls,

Upstream:

As already announced here is the next release! It includes upstream to 4.9.156 and more patches from kernel/common.

Clang:

[MENTION=2489052]NYCHitman1[/MENTION] gave me a hint for a commit, which is needed in order to finally built the kernel with Clang 8.0.8, while keeping CFI and LTO intact!

So now the kernel is built with latest Clang 8.0.8 from Google´s repos. :) Everything is nice and stable still! Kernel size is slightly reduced!

Surprise:

So that alone would usually be worth a new release. However this Monday I made a small discovery, which surprised me a lot.

While doing the upstream F2FS merge, which got introduced in 2.0.0, I benchmarked the filesystem performance quite a lot. Partly to check if there were performance regressions or enhancements and partly to check if any problems with stability surfaced. So I know how the benchmark scores should look like. The f2fs commits were in testing for about 2 months before I decided to release them finally!

Lets take the app androbench as an example from now on to keep things simple.

Usually my scores would look like this:

This Monday I did, more coincidentally, a run of androbench again. I did not play with f2fs or anything file system performance related in my recent releases!

However my result now looked like this suddenly:

Notice the significant drop in almost every area (except sequential writes were it isn´t as severe!).

Sequential reads/writes happen for example, when you copy/paste a movie, or play a movie.

Random read/writes happen when using the phone actually. When opening apps, when multitasking, typing, etc.

With random operations being by far more important to actually using the device, these results put us back to the level of a samsung galaxy s6, which was the absolute king of file system performance back in 2015. (random operations/androbench wise!)

I flashed a whole bunch of test kernels to try to isolate the issue. In the end, I came to the conclusion that it was part of the February Security Update! A tester confirmed this behaviour on stock rom and stock kernel (Februrary Patch State).

So I narrowed it down to the following commit, which indeed got introduced with the February Security Patch!

I never saw the warning in dmesg the commit mentions. It may potentially be that this is solved by an upstream commit we already have.

I decided to revert that potential "fix" as it seems to have a tremendous impact on file system performance, even if it comes from Google or in this case even Jaegeuk Kim in person. (He´s the linux maintainer of F2FS)

The Pixel 3 has one of the fastest filesystems of all phones available and I like my phone to stay that way! :)

Let´s see if Google decides to roll it back next month.

Changelog:

- Linux Stable bumped up to 4.9.156

- Kernel is now built with Clang 8.0.8

- Patches from kernel/common

- Restore original file system performance pre february security update!

Important :)

All flashing errors are now fixed. If you experience the ramdisk error please take a look at the FAQ.

Have fun flashing and enjoy your device with latest linux-stable :)

Why is linux-stable important?

I wish you all a nice day/evening!

Download is below :)

Download:

https://www.androidfilehost.com/?fid=1395089523397892153

or following the link in the op to the correction version

Instructions can be found in the OP!

But look at this post too :)

Have fun, enjoy the kernel and your phone.

If you like my work please consider a donation.

Donations are not mandatory but very welcome.

If you like my work and want to buy me a coffee: http://paypal.me/freak07