# Problems with CPU usage after latest SP4 kernel update

**URL:** <https://forums.suse.com/t/problems-with-cpu-usage-after-latest-sp4-kernel-update/28468>\
**Category:** SLES for System Z\
**Created:** [July 30, 2016, 8:31pm UTC](https://forums.suse.com/t/problems-with-cpu-usage-after-latest-sp4-kernel-update/28468 "2016-07-30T20:31:46Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![atbsigma](https://avatars.discourse-cdn.com/v4/letter/a/41988e/32.png) [@atbsigma](https://forums.suse.com/u/atbsigma)\
**Post date:** [July 30, 2016, 8:31pm UTC](https://forums.suse.com/t/problems-with-cpu-usage-after-latest-sp4-kernel-update/28468/1 "2016-07-30T20:31:46Z")

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I’ve found that after updating our zLinux (s390x) servers with the latest kernel for SuSE 11 SP4 (kernel-default-3.0.101-77.1), a couple of applications start hanging and the CPU races out of control.

It’s caused us to roll back our update of those servers to one of the previous kernels, kernel-default-3.0.101-68.1 or 71.1. I will try and gather more information via strace and lost when I can, but the issue seems to happen during disk accesses, most notably when I attempt to run zipl, as the process attempts to write the new boot loader config to DASD.

Has anyone else had a similar issue with SP4 on Z? Right now we don’t have the luxury of updating our existing servers to SuSE 12 due to stringent requirements for introducing major upgrades to our operating system.

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**Author:** ![Automatic\_Reply](https://avatars.discourse-cdn.com/v4/letter/a/ecb155/32.png) [@Automatic\_Reply](https://forums.suse.com/u/Automatic_Reply)\
**Post date:** [August 5, 2016, 7:30am UTC](https://forums.suse.com/t/problems-with-cpu-usage-after-latest-sp4-kernel-update/28468/2 "2016-08-05T07:30:23Z")

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atbsigma,

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**Author:** ![atbsigma](https://avatars.discourse-cdn.com/v4/letter/a/41988e/32.png) [@atbsigma](https://forums.suse.com/u/atbsigma)\
**Post date:** [August 11, 2016, 8:49am UTC](https://forums.suse.com/t/problems-with-cpu-usage-after-latest-sp4-kernel-update/28468/3 "2016-08-11T08:49:09Z")

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It turns out that the latest kernel update for SLES on Z seems to fix the problem we were having. I’ll read the errata to find out what was changed (or put back!)