From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tanel Kokk <tanel.kokk@gmail.com>
Subject: Re: In kvm, a single process cannot allocate more than 3.6GB ram.
 Why?
Date: Sat, 12 Dec 2009 12:11:00 +0200
Message-ID: <4B236C34.9010302@gmail.com>
References: <4B220ADF.6030709@gmail.com> <4B235A73.9040303@redhat.com> <4B236118.6090305@gmail.com> <4B2363F5.5020103@redhat.com>
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To: Avi Kivity <avi@redhat.com>
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On 12/12/09 11:35, Avi Kivity wrote:
> On 12/12/2009 11:23 AM, Tanel Kokk wrote:
>> On 12/12/09 10:55, Avi Kivity wrote:
>>   
>>> On 12/11/2009 11:03 AM, Tanel Kokk wrote:
>>>     
>>>> Does anybody have a glue why process are not able to allocate more than
>>>> 3.6GB memory ?
>>>>
>>>> What should i do to allow process allocate more than 3.6GB memory?
>>>> Is it
>>>> possible at all?
>>>>
>>>>        
>>> A guest or host process?  And what happens when you try?
>>>      
>> guest process
>>
>> We discovered that if postgres process (on guest) used to use only 3.6GB
>> memory regardless of guest had 8GB memory in common.
>>
>>    
> 
> 
> That's probably a postgres configuration error (or you're using 32-bit
> postgres).

postgres is 64bit:
root@lu2-kvm-db1 ~]# file /usr/lib/postgresql/8.3/bin/postgres
/usr/lib/postgresql/8.3/bin/postgres: ELF 64-bit LSB executable, x86-64,
version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux
2.6.8, not stripped

> 
> 
>> Then I made simple python script, which just eat memory:
>> ------------------------------------
>> #!/usr/bin/python
>> import time, random
>>
>> i = 0
>> while (i<  100000000):
>>      a[i] = random.random()
>>      i = i + 1
>>
>> time.sleep(600)
>> ------------------------------------
>> And I get python MemoryError, when script has devoured about 3.6GB ram
>>    
> 
> 
> Doesn't mean much - Python may allocate a lot more memory when extending
> the array.
> 
> What does 'cat /proc/meminfo' in the guest say?
> 

[root@lu2-kvm-db1 ~]# cat /proc/meminfo
MemTotal:       10267308 kB
MemFree:          228944 kB
Buffers:           19680 kB
Cached:          6069524 kB
SwapCached:            0 kB
Active:          8175200 kB
Inactive:        1374884 kB
Active(anon):    3238044 kB
Inactive(anon):   544104 kB
Active(file):    4937156 kB
Inactive(file):   830780 kB
Unevictable:           0 kB
Mlocked:               0 kB
SwapTotal:             0 kB
SwapFree:              0 kB
Dirty:             15968 kB
Writeback:             0 kB
AnonPages:       3461108 kB
Mapped:           327816 kB
Slab:             171452 kB
SReclaimable:     121756 kB
SUnreclaim:        49696 kB
PageTables:       244268 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:     8727208 kB
Committed_AS:    6056168 kB
VmallocTotal:   34359738367 kB
VmallocUsed:       38180 kB
VmallocChunk:   34359645255 kB
DirectMap4k:        4032 kB
DirectMap2M:    10481664 kB

Tanel