Comment 29 for bug 1519897

The test kernel in comment #13 was built on top of Ubuntu-3.13.0-76.120. It had the 7 commits listed in comment #18 applied. It did not have the performance regression per comment #14.

The test kernel in comment #19 was built on top of Ubuntu-3.13.0-78.122 I had the 7 commits listed in comment #19 reverted, but it also had the 3.13.11-ckt34 stable updates applied. It still had the regression per comment #28.

This may indicated the regression came in via one of the upstream stable updates.

I'd like to perform a kernel bisect between Ubuntu-3.13.0-76.120 and Ubuntu-3.13.0-78.122. However, we first need to make sure Ubuntu-3.13.0-76.120 does not have the performance regression and Ubuntu-3.13.0-78.122 does have the regression.

Can you test these two kernels for confirmation. Once we have the results, we can start the bisect or decide on the next step:

Ubuntu-3.13.0-76.120: https://launchpad.net/~canonical-kernel-security-team/+archive/ubuntu/ppa/+build/8865557

Ubuntu-3.13.0-78.122: https://launchpad.net/~canonical-kernel-team/+archive/ubuntu/ppa/+build/8926054

Note, you need to install both the linux-image and linux-image-extra .deb packages.

In parallel, I will still build you a test kernel with the original 7 commits and commit 757647e applied. I'm in the process of identifying all the prereqs and backporting.