Bug 706328 - with 25GB left kvm refused to create more guests
Summary: with 25GB left kvm refused to create more guests
Keywords:
Status: CLOSED WONTFIX
Alias: None
Product: Red Hat Enterprise Linux 5
Classification: Red Hat
Component: kvm
Version: 5.7
Hardware: x86_64
OS: Linux
medium
medium
Target Milestone: rc
: ---
Assignee: Andrea Arcangeli
QA Contact: Virtualization Bugs
URL:
Whiteboard:
Depends On:
Blocks: Rhel5KvmTier1
TreeView+ depends on / blocked
 
Reported: 2011-05-20 06:29 UTC by Vivian Bian
Modified: 2011-08-15 15:39 UTC (History)
15 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2011-08-15 15:39:55 UTC
Target Upstream Version:
Embargoed:


Attachments (Terms of Use)
/var/log/messages (366.97 KB, text/plain)
2011-05-20 06:29 UTC, Vivian Bian
no flags Details
ps -axv and /proc/meminfo (16.12 KB, application/x-gzip)
2011-05-26 10:13 UTC, Vivian Bian
no flags Details

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.


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