Bug 916968
| Summary: | migration with page compression (xbzrle) on sometimes can not finish (remaining ram: 4 kbytes) | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 7 | Reporter: | Shaolong Hu <shu> |
| Component: | qemu-kvm | Assignee: | Virtualization Maintenance <virt-maint> |
| Status: | CLOSED DUPLICATE | QA Contact: | Virtualization Bugs <virt-bugs> |
| Severity: | medium | Docs Contact: | |
| Priority: | medium | ||
| Version: | 7.0 | CC: | acathrow, juzhang, michen, owasserm, quintela, qzhang, virt-maint |
| Target Milestone: | rc | ||
| Target Release: | --- | ||
| Hardware: | Unspecified | ||
| OS: | Unspecified | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2013-03-01 10:32:01 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: | |||
*** This bug has been marked as a duplicate of bug 893350 *** |
Description of problem: -------------------------- Migration with page compression (xbzrle) on sometimes can not finish (remaining ram: 4 kbytes). Version-Release number of selected component (if applicable): -------------------------------------------------------------- qemu-kvm-1.3.0-5.el7 How reproducible: ------------------ 1/1 Steps to Reproduce: --------------------- 1.on both src host and des host (qemu) migrate_set_cache_size 1G (qemu) migrate_set_capability xbzrle on 2.in guest, add stress with code: #include <stdlib.h> #include <stdio.h> #include <signal.h> int main() { void wakeup(); signal(SIGALRM,wakeup); alarm(300); char *buf = (char *) calloc(40960, 4096); while (1) { int i; for (i = 0; i < 40960 * 4; i++) { buf[i * 4096 / 4]++; } printf("."); } } void wakeup() { exit(0); } 3.after step 2, start migration immediately and set speed limit to 10M: (qemu) migrate -d tcp:0:5555 (qemu) migrate_set_speed 10M 4.migration never ends, get stuck at "remaining ram: 4 kbytes": (qemu) info migrate capabilities: xbzrle: on Migration status: active total time: 341779 milliseconds expected downtime: 638 milliseconds transferred ram: 1399902 kbytes remaining ram: 4 kbytes total ram: 2105728 kbytes duplicate: 542060 pages normal: 214521 pages normal bytes: 858084 kbytes dirty pages rate: 102946 pages cache size: 1073741824 bytes xbzrle transferred: 541289 kbytes xbzrle pages: 30596884 pages xbzrle cache miss: 214497 xbzrle overflow : 24 5.purpose to run the special stress in step 2 and set migration speed to 10M is: to create approximate a quota of dirty page with the code (run 300s then exit), due to dirty page generates quickly enough and migration speed limit, before the code exits, migration won't converge and after codes exits migration converges immediately for there is no more workload, i planed to compare the performance of xbzrle=on/off with this method, however run into this problem, i think with common stress the issue can also be reproduced. 6.if turn off xbzrle, won't hit the problem.