On 04.02.2016 21:11, Jiri Denemark wrote:
> On Thu, Jan 28, 2016 at 10:04:29 +0300, Nikolay Shirokovskiy wrote:
>> From: ShaoHe Feng <shaohe.feng@xxxxxxxxx>
>>
>> Current compression does not use all range of parameter values
>> so let's use some of them as 'unspecified' values. These
>> values will be used to mark parameters that were not specified
>> on migrate command line. Thus we check that qemu does not
>> use these values when we read parameters.
>>
>> Signed-off-by: ShaoHe Feng <shaohe.feng@xxxxxxxxx>
>> Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy@xxxxxxxxxxxxx>
>> ---
>> src/qemu/qemu_monitor.c | 29 +++++++++++++
>> src/qemu/qemu_monitor.h | 16 +++++++
>> src/qemu/qemu_monitor_json.c | 87 +++++++++++++++++++++++++++++++++++++
>> src/qemu/qemu_monitor_json.h | 5 +++
>> src/qemu/qemu_monitor_text.c | 100 +++++++++++++++++++++++++++++++++++++++++++
>> src/qemu/qemu_monitor_text.h | 5 +++
>
>>
>>
>> int
>> +qemuMonitorGetMigrationCompressParametersMT(qemuMonitorPtr mon,
>> + qemuMonitorMigrationMTParametersPtr params)
>
> I think a more general qemuMonitor[GS]etMigrationParameters [gs]etting
> all parameters at once would be a bit better. After all, it all boils
> down to query-migrate-parameters and migrate-set-parameters and having
> separate functions for each group of parameters would mean we'd have to
> call the QMP commands several times.
AFAIK it is not so. We can't set(get) xbzrle options (only size now) and
multithread options togather. We neet "query-migrate-cache-size" for the
first and "query-migrate-parameters" for the second.
>> +int qemuMonitorJSONSetMigrationCompressParametersMT(qemuMonitorPtr mon,
>> + qemuMonitorMigrationMTParametersPtr params)
>> +{
>> + int ret = -1;
>> + virJSONValuePtr cmd;
>> + virJSONValuePtr reply = NULL;
>> +
>> + cmd = qemuMonitorJSONMakeCommand("migrate-set-parameters",
>> + "i:compress-level", params->level,
>> + "u:compress-threads", params->threads,
>> + "u:decompress-threads", params->dthreads,
>> + NULL);
>
> Is passing an "undefined" value for any of these parameters allowed
> (i.e., will QEMU use a default value) or do we always have to set all of
> them?
QEMU is good enough to take partial parameters specs. In this case the other
just stay untouched. But I never use this command in this mode and specify
all parameters. I do it to make sure we don't get compression parameters
from previous failed migration attempt. See patch number 5.
Basically instead of reverting parameters on unsuccessful migration
I use hardcoded default values for parameters that are not specified on migration.
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