[libvirt] [PATCH 2/2] qemu: Adaptive timeout for connecting to monitor

[Jim Fehlig]

Michal Privoznik wrote:
> On 03/15/2017 02:16 AM, Jim Fehlig wrote:
>> On 03/13/2017 06:29 AM, Michal Privoznik wrote:
>>> There were couple of reports on the list (e.g. [1]) that guests
>>> with huge amounts of RAM are unable to start because libvirt
>>> kills qemu in the initialization phase. The problem is that if
>>> guest is configured to use hugepages kernel has to zero them all
>>> out before handing over to qemu process. For instance, 402GiB
>>> worth of 1GiB pages took around 105 seconds (~3.8GiB/s). Since we
>>> do not want to make the timeout for connecting to monitor
>>> configurable [2], we have to teach libvirt to count with this
>>> fact. This commit implements "1s per each 1GiB of RAM" approach
>>> as suggested here [3].
>> FYI, on another machine I observed ~1.5 seconds for each 5G of memory.
>>
>>> 1: https://www.redhat.com/archives/libvir-list/2017-March/msg00373.html
>>> 3: https://www.redhat.com/archives/libvir-list/2017-March/msg00405.html
>>>
>>> 2: The reason is that ideally someday it will be Libvirt who
>>> creates the monitor socket and qemu will just use it.
>> This point isn't clear to me wrt the changes done by the commit.
> 
> Okay, I can remove it.
> 
>>> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
>>> ---
>>>  src/qemu/qemu_capabilities.c |  2 +-
>>>  src/qemu/qemu_monitor.c      | 36 +++++++++++++++++++++++++++++++-----
>>>  src/qemu/qemu_monitor.h      |  1 +
>>>  src/qemu/qemu_process.c      |  8 ++++++++
>>>  tests/qemumonitortestutils.c |  1 +
>>>  5 files changed, 42 insertions(+), 6 deletions(-)
>>>
> 
> 
>> Looks good. You can decide about the nits. ACK in principle, but I'm not
>> able to test this ATM. The host I was using is now running a VM that
>> uses most of its memory. Matt might be running a test in that VM so I
>> don't want to kill it :-). I can test the patches tomorrow and report
>> back if you want to wait a bit before pushing.
> 
> Sure. I will wait for your report and thus full ACK.

Test results were positive. ACK series.

Regards,
Jim