Bug 796575
| Summary: | qemu-kvm wakes up 66 times a second | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 6 | Reporter: | Paolo Bonzini <pbonzini> |
| Component: | qemu-kvm | Assignee: | Paolo Bonzini <pbonzini> |
| Status: | CLOSED ERRATA | QA Contact: | Virtualization Bugs <virt-bugs> |
| Severity: | unspecified | Docs Contact: | |
| Priority: | unspecified | ||
| Version: | 6.3 | CC: | acathrow, bsarathy, drjones, gleb, juzhang, knoel, kraxel, minovotn, mkenneth, pbonzini, pportant, virt-maint, xfu |
| Target Milestone: | rc | ||
| Target Release: | --- | ||
| Hardware: | Unspecified | ||
| OS: | Unspecified | ||
| Whiteboard: | |||
| Fixed In Version: | qemu-kvm-0.12.1.2-2.240.el6 | Doc Type: | Bug Fix |
| Doc Text: |
Cause: QEMU used to require periodic polling for events.
Consequence: QEMU would wake up many times per seconds.
Fix: Since QEMU sets up specific timers when it requires to poll for events, the generic polling timer was removed.
Resolution: An idle guest, with no VNC or SPICE connection active, will not wake up the QEMU process unnecessarily.
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Story Points: | --- |
| Clone Of: | Environment: | ||
| Last Closed: | 2012-06-20 11:43:51 UTC | Type: | --- |
| 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
Paolo Bonzini
2012-02-23 08:43:40 UTC
Reproduced this issue with qemu-kvm-0.12.1.2-2.233.el6 1. boot guest with -vnc 2. close vnc console 3. collecting timer_settime in 10 seconds Results: strace -c -p `pidof qemu-kvm` Process 20299 attached - interrupt to quit ^CProcess 20299 detached % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 91.03 0.021183 13 1621 select 3.52 0.000819 1 1479 write 2.95 0.000686 0 4537 2211 read 1.53 0.000355 1 693 rt_sigaction 0.88 0.000204 0 1040 timer_gettime 0.10 0.000024 0 693 timer_settime 0.00 0.000000 0 1 mmap 0.00 0.000000 0 1 mprotect 0.00 0.000000 0 8 rt_sigprocmask 0.00 0.000000 0 45 ioctl 0.00 0.000000 0 2 writev 0.00 0.000000 0 4 clone 0.00 0.000000 0 51 2 futex ------ ----------- ----------- --------- --------- ---------------- 100.00 0.023271 10175 2213 total Verified this issue with qemu-kvm-0.12.1.2-2.282.el6 Results: strace -c -p `pidof qemu-kvm` Process 20046 attached - interrupt to quit ^CProcess 20046 detached % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 98.74 0.013998 105 133 select 0.71 0.000101 0 340 163 read 0.48 0.000068 1 84 write 0.07 0.000010 0 60 timer_gettime 0.00 0.000000 0 40 rt_sigaction 0.00 0.000000 0 25 ioctl 0.00 0.000000 0 1 writev 0.00 0.000000 0 10 1 futex 0.00 0.000000 0 40 timer_settime ------ ----------- ----------- --------- --------- ---------------- 100.00 0.014177 733 164 total Summary with fixed version, the timer_gettime and timer_settime calls times from "1040","693" to "60","40". any way, this issue is fixed.
Technical note added. If any revisions are required, please edit the "Technical Notes" field
accordingly. All revisions will be proofread by the Engineering Content Services team.
New Contents:
NEEDINFO
Technical note updated. If any revisions are required, please edit the "Technical Notes" field
accordingly. All revisions will be proofread by the Engineering Content Services team.
Diffed Contents:
@@ -1 +1,7 @@
-NEEDINFO+Cause: QEMU used to require periodic polling for events.
+
+Consequence: QEMU would wake up many times per seconds.
+
+Fix: Since QEMU sets up specific timers when it requires to poll for events, the generic polling timer was removed.
+
+Resolution: An idle guest, with no VNC or SPICE connection active, will not wake up the QEMU process unnecessarily.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. http://rhn.redhat.com/errata/RHBA-2012-0746.html |