Re: [Qemu-devel] Qemu and heavily increased RSS usage

[Paolo Bonzini]

On 23/06/2016 17:31, Peter Lieven wrote:
> Am 23.06.2016 um 17:21 schrieb Paolo Bonzini:
>>
>> On 23/06/2016 16:58, Peter Lieven wrote:
>>> commit ba3f4f64b0e941b9e03568b826746941bef071f9
>>> Author: Paolo Bonzini <address@hidden>
>>> Date:   Wed Jan 21 12:09:14 2015 +0100
>>>
>>>      exec: RCUify AddressSpaceDispatch
>>>
>>>      Note that even after this patch, most callers of address_space_*
>>>      functions must still be under the big QEMU lock, otherwise the
>>> memory
>>>      region returned by address_space_translate can disappear as soon as
>>>      address_space_translate returns.  This will be fixed in the next
>>> part
>>>      of this series.
>>>
>>>      Reviewed-by: Fam Zheng <address@hidden>
>>>      Signed-off-by: Paolo Bonzini <address@hidden>
>>>
>>> @Paolo, @Fam, any idea?
>> When you use RCU, freeing stuff is delayed a bit.
> 
> define a bit?
> 
> I face the issue that it seems (some) stuff is actually never freed...

Can you confirm that with e.g. valgrind?  It could be that malloc has
asked the kernel for more RSS and never released that, but QEMU did free
the memory.

Paolo

> Consider the following simple vServer:
> 
> ./x86_64-softmmu/qemu-system-x86_64 -enable-kvm -M pc-i440fx-2.1
> -nodefaults -serial null -parallel null -m 4096 -smp
> 4,sockets=1,cores=4,threads=1 -monitor tcp:0:4004,server,nowait,nodelay
> -mem-path /hugepages -mem-prealloc -cpu Westmere,enforce -rtc base=utc
> -no-hpet -vga vmware -pidfile /tmp/qemu.pid
> 
> head at 9d82b5a
> 
> VmHWM:       22660 kB
> VmRSS:       22656 kB
> 
> head at 79e2b9a
> 
> VmHWM:       32948 kB
> VmRSS:       32948 kB
> 
> even after several minutes.
> 
> Thanks,
> Peter
>