Bug 12603 - Performance regression with new kernel upgrade
Summary: Performance regression with new kernel upgrade
Status: RESOLVED FIXED
Alias: None
Product: OE-Core
Classification: Build System, Metadata & Runtime
Component: kernel (show other bugs)
Version: 2.5
Hardware: x86 Multiple
: Undecided normal
Target Milestone: ---
Assignee: Bruce Ashfield
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Reported: 2018-03-14 03:48 UTC by Ross Burton
Modified: 2018-03-15 07:54 UTC (History)
1 user (show)

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OS type for building Yocto: ---
Type of Regression: ---
Verified:
Documentation change: No (bug/feature does not impact docs)

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Description Ross Burton 2018-03-14 03:48:46 UTC 
Since the last kernel upgrade in oe-core 62acf087dca83ff094b1c0300b5752978807ca17 the speed of building the kernel changed massively.

buildstats-diff output of the that commit and before the kernel bumps:

  PKG            TASK                      ABSDIFF   RELDIFF  CPUTIME1 -> CPUTIME2
  linux-yocto    do_package                  22.3s   +194.7%     11.5s -> 33.8s
  linux-yocto    do_deploy                   30.1s  +1557.3%      1.9s -> 32.0s
  linux-yocto    do_package_write_ipk       135.0s   +348.8%     38.7s -> 173.7s
  linux-yocto    do_compile_kernelmodules   142.0s    +17.8%    799.7s -> 941.8s
  linux-yocto    do_package_write_rpm       158.9s   +574.1%     27.7s -> 186.6s
  linux-yocto    do_compile                 174.7s    +18.7%    933.3s -> 1108.0s

Longer to compile, a lot longer to deploy and package.
Comment 1 Ross Burton 2018-03-14 05:42:49 UTC 
The problem is the 'linux-yocto: aufs and systemtap' commit which enables CONFIG_KERNEL_DEBUG.

packages/qemux86-poky-linux/linux-yocto/kernel-vmlinux: PKGSIZE changed from 19587044 to 300944172 (+1436%)

Yes, that's 19M to 300M.
Comment 2 Bruce Ashfield 2018-03-14 05:54:33 UTC 
I'll revert the patch that enabled debug, and send it along shortly.
Comment 3 Ross Burton 2018-03-15 07:54:27 UTC 
Fixed in oe-core ad8f68e9831c57fde62f7b1942bfa9e1307f113d