9:36 p.m.
On 2/12/2020 10:56 AM, Jason Wang wrote:
On 2020/2/11 下午4:58, Zhang, Chen wrote:
>> -----Original Message-----
>> From: Jason Wang<jasowang(a)redhat.com>
>> Sent: Monday, January 20, 2020 10:57 AM
>> To: Zhang, Chen<chen.zhang(a)intel.com>; Paolo Bonzini
>> <pbonzini(a)redhat.com>; Philippe Mathieu-Daudé<philmd(a)redhat.com>;
>> qemu-dev<qemu-devel(a)nongnu.org>
>> Cc: Zhang Chen<zhangckid(a)gmail.com>
>> Subject: Re: [PATCH V4 0/5] Introduce Advanced Watch Dog module
>>
>>
>> On 2020/1/19 下午5:10, Zhang, Chen wrote:
>>> Hi~
>>>
>>> Anyone have comments about this module?
>> Hi Chen:
>>
>> I will take a look at this series.
> Sorry for slow reply due to CNY and extend leave.
> OK, waiting your comments~ Thanks~
>
>> Two general questions:
>>
>> - if it can detect more than network stall, it should not belong to /net
> This module use network connection status to detect all the issue(Host to Guest/Host
to Host/Host to Admin...).
> The target is more than network but all use network way. So it is looks a tricky
problem.
Ok.
>> - need to convince libvirt guys for this proposal, since usually it's the
duty of
>> upper layer instead of qemu itself
>>
> Yes, It looks a upper layer responsibility, but In the cover latter I have explained
the reason why we need this in Qemu.
> try to make this module as simple as possible. This module give upper layer
software a new way to connect/monitoring Qemu.
> And due to all the COLO code implement in Qemu side, Many customer want to use this
FT solution without other dependencies,
> it is very easy to integrated to real product.
>
> Thanks
> Zhang Chen
I would like to hear from libvirt about such design.
Hi Jason,
OK. I add the libvirt mailing list in this thread.
The full mail discussion and patches:
https://lists.nongnu.org/archive/html/qemu-devel/2020-02/msg02611.html
By the way, I noticed Eric is libvirt maintianer.
Hi Eric and Paolo, Can you give some comments about this series?
Thanks
Zhang Chen
Thanks
2:06 a.m.
New subject: [PATCH V4 0/5] Introduce Advanced Watch Dog module
>>> Subject: Re: [PATCH V4 0/5] Introduce Advanced Watch Dog
module
>>>
>>>
>>> On 2020/1/19 下午5:10, Zhang, Chen wrote:
>>>> Hi~
>>>>
>>>> Anyone have comments about this module?
>>> Hi Chen:
>>>
>>> I will take a look at this series.
>> Sorry for slow reply due to CNY and extend leave.
>> OK, waiting your comments~ Thanks~
>>
>>> Two general questions:
>>>
>>> - if it can detect more than network stall, it should not belong to
>>> /net
>> This module use network connection status to detect all the issue(Host to
Guest/Host to Host/Host to Admin...).
>> The target is more than network but all use network way. So it is looks a
tricky problem.
>
> Ok.
>
>
>>> - need to convince libvirt guys for this proposal, since usually
>>> it's the duty of upper layer instead of qemu itself
>>>
>> Yes, It looks a upper layer responsibility, but In the cover latter I have
explained the reason why we need this in Qemu.
>> try to make this module as simple as possible. This module give upper
layer software a new way to connect/monitoring Qemu.
>> And due to all the COLO code implement in Qemu side, Many customer
>> want to use this FT solution without other dependencies, it is very easy to
integrated to real product.
>>
>> Thanks
>> Zhang Chen
>
> I would like to hear from libvirt about such design.
Hi Jason,
OK. I add the libvirt mailing list in this thread.
The full mail discussion and patches:
https://lists.nongnu.org/archive/html/qemu-devel/2020-02/msg02611.html
By the way, I noticed Eric is libvirt maintianer.
Hi Eric and Paolo, Can you give some comments about this series?
No news for a while...
We already have some users(Cloud Service Provider) try to use is module in their product.
But they also need to follow the Qemu upstream code.
Thanks
Zhang Chen
Thanks
Zhang Chen
>
> Thanks
>
7:37 a.m.
New subject: [PATCH V4 0/5] Introduce Advanced Watch Dog module
On 04/03/20 09:06, Zhang, Chen wrote:
> Hi Eric and Paolo, Can you give some comments about this series?
>
>
No news for a while...
We already have some users(Cloud Service Provider) try to use is module in their
product.
But they also need to follow the Qemu upstream code.
My main comment about this series is that it's not clear why it is
needed and how to use it. The documentation includes a demo, but no
description of what is an awd_node, a notification_node and an
opt_script. I can more or less understand the notification_node and
opt_script role from the documentation, but not entirely because, for
example, the two-host demo has hardcoded IP addresses without saying
which host is which IP address.
The documentation does not describe the protocol, which is absolutely
necessary, and does not describe _why_ the protocol was designed like
that. Without such documentation it's not clear if, for example, the
watchdog protocol could be implemented as QMP commands (e.g.
start-watchdog, stop-watchdog, notify-watchdog). Another possibility
could be to use the systemd watchdog protocol, which consists of
essentially three commands (WATCHDOG=1, WATCHDOG=trigger,
WATCHDOG_USEC=...) which are transmitted as datagrams. Documentation is
important for reviewers to judge the merits of the protocol without (or
before) diving into the code.
In the demo, the opt_script mechanism is currently using the "human"
monitor as opposed to QMP. The human monitor interface is not stable
and not meant for consumption by management interface. It is not clear
if this is just a sample usage, and in practice the notification_node
would be outside of QEMU, or not. In general I would prefer to have the
script as an optional feature, and report the triggering of the watchdog
via QMP events.
Paolo
4:32 a.m.
New subject: [PATCH V4 0/5] Introduce Advanced Watch Dog module
On 3/4/2020 9:37 PM, Paolo Bonzini wrote:
On 04/03/20 09:06, Zhang, Chen wrote:
>> Hi Eric and Paolo, Can you give some comments about this series?
>>
>>
> No news for a while...
> We already have some users(Cloud Service Provider) try to use is module in their
product.
> But they also need to follow the Qemu upstream code.
My main comment about this series is that it's not clear why it is
needed and how to use it. The documentation includes a demo, but no
description of what is an awd_node, a notification_node and an
opt_script. I can more or less understand the notification_node and
opt_script role from the documentation, but not entirely because, for
example, the two-host demo has hardcoded IP addresses without saying
which host is which IP address.
Hi Paolo,
Sorry for slow reply and thank you for your comments.
Let me summarize your main opinions and methods:
1. Why AWD is needed.
Advanced Watch Dog is an universal monitoring module on VMM side, it can
be used to detect network down(VMM to guest, VMM to VMM, VMM to another
remote server) and do previously set operation. Current AWD patch just
accept any input as the signal to refresh the watchdog timer, and we can
also make a certain interactive protocol here. For the outputs, user can
pre-write some command or some messages in the AWD opt-script. We
noticed that there is no way for VMM communicate directly, maybe some
people think we don't need such things(up layer software like openstack
can handle it). so we engaged with real customer found that they need a
lightweight and efficient mechanism to solve some practical problems,
For example Edge Computing cases(they think high level software is too
heavy to use in Edge or it is hard to manage and combine with VM instance).
It make user have basic VM/Host network monitoring tools and basic false
tolerance and recovery solution.
For COLO FT/HA solution, we already have some CSPs try to use AWD with COLO.
2. Documentation issues, include how to use it.
I will address all your comments and complete details about documentation.
3. Communication protocol issue.
Current AWD without any protocol, any data it gets will be considered a
heartbeat signal.
I think use QMP format is good for me.
4. Implementation issue.
The AWD script as an optional feature is OK for me.
And report the triggering of the watchdog via QMP events is enough for
current usage.
But it looks have limitation to notify outside Qemu. I don't know which
is better choice.
If the QMP events solution is better, I will fix it in next version.
I don't know if I understand your means correctly.
Please give me more guidance on this series. :-)
Thanks
Zhang Chen
The documentation does not describe the protocol, which is absolutely
necessary, and does not describe _why_ the protocol was designed like
that. Without such documentation it's not clear if, for example, the
watchdog protocol could be implemented as QMP commands (e.g.
start-watchdog, stop-watchdog, notify-watchdog). Another possibility
could be to use the systemd watchdog protocol, which consists of
essentially three commands (WATCHDOG=1, WATCHDOG=trigger,
WATCHDOG_USEC=...) which are transmitted as datagrams. Documentation is
important for reviewers to judge the merits of the protocol without (or
before) diving into the code.
In the demo, the opt_script mechanism is currently using the "human"
monitor as opposed to QMP. The human monitor interface is not stable
and not meant for consumption by management interface. It is not clear
if this is just a sample usage, and in practice the notification_node
would be outside of QEMU, or not. In general I would prefer to have the
script as an optional feature, and report the triggering of the watchdog
via QMP events.
Paolo
10:52 a.m.
New subject: [PATCH V4 0/5] Introduce Advanced Watch Dog module
On 09/03/20 10:32, Zhang, Chen wrote:
4. Implementation issue.
The AWD script as an optional feature is OK for me.
And report the triggering of the watchdog via QMP events is enough for
current usage.
But it looks have limitation to notify outside Qemu. I don't know which
is better choice.
If the QMP events solution is better, I will fix it in next version.
Good, thanks.
Naming-wise, it's ugly that we already have a WATCHDOG event for guest
watchdog devices. The following design however should allow setting up
multiple watchdogs
- Creating a watchdog from the command line:
-object watchdog,id=STR,timeout=NNN,chardev=CHR
and object_add/object-add can also be used for HMP and QMP.
- Reporting a watchdog timeout via QMP:
{ 'event': 'WATCHDOG_TIMEOUT',
'data': { 'id': 'str' } }
- Protocol: the data sent on the chardev to QEMU must be
WATCHDOG=1
optionally followed by exactly one \n character. All other data is ignored.
Paolo
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