Bug 1446372
| Summary: | Setting guest's emulatorpin cpuset to the union of all vcpus can have negative performance impact | ||
|---|---|---|---|
| Product: | Red Hat OpenStack | Reporter: | Jean-Tsung Hsiao <jhsiao> |
| Component: | openstack-nova | Assignee: | Eoghan Glynn <eglynn> |
| Status: | CLOSED DUPLICATE | QA Contact: | Prasanth Anbalagan <panbalag> |
| Severity: | high | Docs Contact: | |
| Priority: | unspecified | ||
| Version: | 10.0 (Newton) | CC: | atelang, berrange, dasmith, eglynn, jhsiao, kchamart, sbauza, sferdjao, sgordon, srevivo, vromanso, yrachman |
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | x86_64 | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | If docs needed, set a value | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2017-04-28 15:35:44 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: | |||
Is there a way to change this default ? (In reply to Jean-Tsung Hsiao from comment #0) > Description of problem: Setting guest's emulatorpin cpuset to the union of > all vcpus can have negative performance impact > > <vcpu placement='static'>4</vcpu> > <cputune> > <shares>4096</shares> > <vcpupin vcpu='0' cpuset='3'/> > <vcpupin vcpu='1' cpuset='15'/> > <vcpupin vcpu='2' cpuset='1'/> > <vcpupin vcpu='3' cpuset='13'/> > <emulatorpin cpuset='1,3,13,15'/> > </cputune> > > This default setting can cause performance impact, especially on 64 bytes > zero loss Mpps rate. In RHOS 12 (bug 1298079) a feature has been integrated to isolate emulator threads [0] on a additional physical CPU, is that what you are looking for ? Also depending of your use-case (I do not know what is a 64 bytes zero loss Mpps rate) the realtime feature provides a mask which isolates emulator threads on a set of CPUs. [0] https://specs.openstack.org/openstack/nova-specs/specs/ocata/approved/libvirt-emulator-threads-policy.html [1] https://specs.openstack.org/openstack/nova-specs/specs/mitaka/implemented/libvirt-real-time.html (In reply to Sahid Ferdjaoui from comment #2) > (In reply to Jean-Tsung Hsiao from comment #0) > > Description of problem: Setting guest's emulatorpin cpuset to the union of > > all vcpus can have negative performance impact > > > > <vcpu placement='static'>4</vcpu> > > <cputune> > > <shares>4096</shares> > > <vcpupin vcpu='0' cpuset='3'/> > > <vcpupin vcpu='1' cpuset='15'/> > > <vcpupin vcpu='2' cpuset='1'/> > > <vcpupin vcpu='3' cpuset='13'/> > > <emulatorpin cpuset='1,3,13,15'/> > > </cputune> > > > > This default setting can cause performance impact, especially on 64 bytes > > zero loss Mpps rate. > > In RHOS 12 (bug 1298079) a feature has been integrated to isolate emulator > threads [0] on a additional physical CPU, is that what you are looking for ? Yes. I'll read bug 1298079. Thanks! Jean > > Also depending of your use-case (I do not know what is a 64 bytes zero loss > Mpps rate) the realtime feature provides a mask which isolates emulator > threads on a set of CPUs. > > [0] > https://specs.openstack.org/openstack/nova-specs/specs/ocata/approved/ > libvirt-emulator-threads-policy.html > [1] > https://specs.openstack.org/openstack/nova-specs/specs/mitaka/implemented/ > libvirt-real-time.html This is a duplicate of bug 1298079. *** This bug has been marked as a duplicate of bug 1298079 *** |
Description of problem: Setting guest's emulatorpin cpuset to the union of all vcpus can have negative performance impact <vcpu placement='static'>4</vcpu> <cputune> <shares>4096</shares> <vcpupin vcpu='0' cpuset='3'/> <vcpupin vcpu='1' cpuset='15'/> <vcpupin vcpu='2' cpuset='1'/> <vcpupin vcpu='3' cpuset='13'/> <emulatorpin cpuset='1,3,13,15'/> </cputune> This default setting can cause performance impact, especially on 64 bytes zero loss Mpps rate. Version-Release number of selected component (if applicable): OSP10 Release How reproducible:reproducible Steps to Reproduce: 1. Configure NFV guest. 2. Look at it xml file. 3. Actual results: Expected results: Additional info: