Bug 1109113
| Summary: | configuration improvement CONFIG_RCU_NOCB_CPU | ||
|---|---|---|---|
| Product: | [Fedora] Fedora | Reporter: | Morten Stevens <ms> |
| Component: | kernel | Assignee: | Kernel Maintainer List <kernel-maint> |
| Status: | CLOSED RAWHIDE | QA Contact: | Fedora Extras Quality Assurance <extras-qa> |
| Severity: | unspecified | Docs Contact: | |
| Priority: | unspecified | ||
| Version: | rawhide | CC: | gansalmon, itamar, jonathan, kernel-maint, madhu.chinakonda, mchehab |
| Target Milestone: | --- | Keywords: | FutureFeature, Triaged |
| Target Release: | --- | ||
| Hardware: | Unspecified | ||
| OS: | Unspecified | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Enhancement | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2014-06-17 16:46:17 UTC | Type: | Bug |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
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Description
Morten Stevens
2014-06-13 09:32:00 UTC
You forgot to say why that should be enabled. (In reply to Josh Boyer from comment #1) > You forgot to say why that should be enabled. Hi Josh, This is a new kernel option (since 3.10?) and reduces OS jitter for aggressive HPC or real-time workloads. It's also enabled on RHEL 7. CONFIG_RCU_NOCB_CPU=y CONFIG_RCU_NOCB_CPU_ALL=y Right. Fedora isn't typically used extensively in either of those cases, which is why we left it off. (In reply to Josh Boyer from comment #3) > Right. Fedora isn't typically used extensively in either of those cases, > which is why we left it off. It has no negative impact to Fedora and for example Ubuntu 14.04 has it also enabled. Why not enable it for Fedora?! I didn't say we wouldn't look at enabling it. I gave reason why it was left disabled originally. At any rate, we're not going to flip this on in the middle of a stable release. If it's done it will be done in rawhide. (In reply to Josh Boyer from comment #5) > I didn't say we wouldn't look at enabling it. I gave reason why it was left > disabled originally. Okay, thank you. > At any rate, we're not going to flip this on in the middle of a stable > release. If it's done it will be done in rawhide. I would be happy to see it in rawhide. Do you plan a kernel 3.15 rebase for Fedora 20? Would it be possible to enable it also for F20 with the upcoming 3.15 rebase? I enabled this in today's Rawhide kernel. Should hit the repos tomorrow. We're likely not going to enable this in F20 with the 3.15 rebase. We'll wait and see what happens with rawhide first. (In reply to Josh Boyer from comment #7) > I enabled this in today's Rawhide kernel. Should hit the repos tomorrow. Okay, but CONFIG_RCU_NOCB_CPU_ALL is not set. [root@fc20 boot]# cat config-3.16.0-0.rc0.git11.1.fc21.x86_64 | grep CONFIG_RCU_ NOCB_CPU_ALL # CONFIG_RCU_NOCB_CPU_ALL is not set Oops. Yes, my mistake. I'll turn that on with today's 3.16-rc1 build. Hi Josh, All right. The latest 3.16.0-0.rc1.git0.1.fc21.x86_64 kernel with CONFIG_RCU_NOCB_CPU=y and CONFIG_RCU_NOCB_CPU_ALL=y works fine for me. In my opinion, this is a stable feature (also enabled in RHEL 7.0 and Ubuntu 14.04 LTS) so it would be nice to have it also enabled with the next kernel 3.15 rebase for F20. Thanks for testing. We'll evaluate f20 later. |