Bug 706328

Summary: with 25GB left kvm refused to create more guests
Product: Red Hat Enterprise Linux 5 Reporter: Vivian Bian <vbian>
Component: kvmAssignee: Andrea Arcangeli <aarcange>
Status: CLOSED WONTFIX QA Contact: Virtualization Bugs <virt-bugs>
Severity: medium Docs Contact:
Priority: medium    
Version: 5.7CC: aarcange, ajia, apevec, danken, dyuan, gcosta, jdenemar, juzhang, llim, michen, mkenneth, mshao, rhod, veillard, virt-maint
Target Milestone: rc   
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2011-08-15 15:39:55 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:
Bug Depends On:    
Bug Blocks: 580949    
Attachments:
Description Flags
/var/log/messages
none
ps -axv and /proc/meminfo none

Description Vivian Bian 2011-05-20 06:29:48 UTC
Created attachment 500001 [details]
/var/log/messages

Description of problem:
Tried to create 1000 guests on the machine with 64 cores CPU and 512GB memory . But after successful creation of 512 guests , was told error: internal error Process exited while reading console log output: kvm_create_vm: Cannot allocate memory Could not create KVM context . 

When the error happened , checked with free 
# # free -lm
             total       used       free     shared    buffers     cached
Mem:        516238     490302      25935          0       1215     440519
Low:        516238     490302      25935
High:            0          0          0
-/+ buffers/cache:      48568     467670
Swap:        34239          0      34239

it says there are still 25GB left . command "top" shows every qemu-kvm process use 0.0% memory

And also atm , selinux status was Permissive . 

Version-Release number of selected component (if applicable):
kvm-83-230.el5

How reproducible:
Always

Steps to Reproduce:
1.try to start 1000 guests on 512GB memory machine 
2.
3.
  
Actual results:


Expected results:


Additional info:

Comment 1 Vivian Bian 2011-05-20 06:38:00 UTC
each guest is with 512MB vMemory and 1 vCPU configured .

Comment 2 Andrea Arcangeli 2011-05-25 17:11:30 UTC
Hello Vivan,

could you post /proc/meminfo and ps xav too, when this happens?

Comment 4 Vivian Bian 2011-05-26 10:13:33 UTC
Created attachment 501038 [details]
ps -axv and /proc/meminfo

(In reply to comment #3)
> Could you also check if "echo 1 >/proc/sys/vm/overcommit_memory" workaround
> that and then everything works fine?

with echo command executed , still meet kvm_create_vm: Cannot allocate memory
Could not create KVM context errors

Comment 9 Ronen Hod 2011-08-15 15:39:55 UTC
Given our strict 5.8 bug fixing criteria, it seems as if we can survive without handling this issue.
Closing.