Bug 706328 - with 25GB left kvm refused to create more guests
with 25GB left kvm refused to create more guests
Product: Red Hat Enterprise Linux 5
Classification: Red Hat
Component: kvm (Show other bugs)
x86_64 Linux
medium Severity medium
: rc
: ---
Assigned To: Andrea Arcangeli
Virtualization Bugs
Depends On:
Blocks: Rhel5KvmTier1
  Show dependency treegraph
Reported: 2011-05-20 02:29 EDT by Vivian Bian
Modified: 2011-08-15 11:39 EDT (History)
15 users (show)

See Also:
Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
Last Closed: 2011-08-15 11:39:55 EDT
Type: ---
Regression: ---
Mount Type: ---
Documentation: ---
Verified Versions:
Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

Attachments (Terms of Use)
/var/log/messages (366.97 KB, text/plain)
2011-05-20 02:29 EDT, Vivian Bian
no flags Details
ps -axv and /proc/meminfo (16.12 KB, application/x-gzip)
2011-05-26 06:13 EDT, Vivian Bian
no flags Details

  None (edit)
Description Vivian Bian 2011-05-20 02:29:48 EDT
Created attachment 500001 [details]

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):

How reproducible:

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

Expected results:

Additional info:
Comment 1 Vivian Bian 2011-05-20 02:38:00 EDT
each guest is with 512MB vMemory and 1 vCPU configured .
Comment 2 Andrea Arcangeli 2011-05-25 13:11:30 EDT
Hello Vivan,

could you post /proc/meminfo and ps xav too, when this happens?
Comment 4 Vivian Bian 2011-05-26 06:13:33 EDT
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 11:39:55 EDT
Given our strict 5.8 bug fixing criteria, it seems as if we can survive without handling this issue.

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