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From: Juan Quintela <quintela@redhat.com>
In-Reply-To: <20171009081938.GD2196@pxdev.xzpeter.org> (Peter Xu's message of
	"Mon, 9 Oct 2017 16:19:38 +0800")
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	<20171004103933.7898-2-quintela@redhat.com>
	<20171009081938.GD2196@pxdev.xzpeter.org>
Reply-To: quintela@redhat.com
Date: Wed, 18 Oct 2017 13:49:42 +0200
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Subject: Re: [Qemu-devel] [PATCH 1/6] tests: Add basic migration precopy test
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To: Peter Xu <peterx@redhat.com>
Cc: qemu-devel@nongnu.org, dgilbert@redhat.com, lvivier@redhat.com

Peter Xu <peterx@redhat.com> wrote:
> On Wed, Oct 04, 2017 at 12:39:28PM +0200, Juan Quintela wrote:
>
> [...]
>
> (having some unit tests for migration is really good...)
>
>> +static void test_precopy(const char *uri)
>> +{
>> +    QTestState *from, *to;
>> +
>> +    test_migrate_start(&from, &to, uri);
>> +
>> +    /* We want to pick a speed slow enough that the test completes
>> +     * quickly, but that it doesn't complete precopy even on a slow
>> +     * machine, so also set the downtime.
>> +     */
>> +    /* 100 ms */
>> +    migrate_set_parameter(from, "downtime-limit", "100");
>> +    /* 1MB/s slow*/
>
> This is 100MB/s?
>
>> +    migrate_set_parameter(from, "max-bandwidth", "100000000");
>> +
>> +    /* Wait for the first serial output from the source */
>> +    wait_for_serial("src_serial");
>> +
>> +    migrate(from, uri);
>> +
>> +    wait_for_migration_pass(from);
>> +
>> +    /* 1GB/s now it should converge */
>> +    migrate_set_parameter(from, "max-bandwidth", "1000000000");
>
> Curious: would it possible that 1GB/s won't suffice in some cases?
> Is there any reason behind this 1GB/s value?

No.

My new test setup just uses 1GB/s

and plays with the downtime (1ms) while I want to wait for one full
cycle
and then 300ms.

Notice that the guest is around 100MB of size, so ....


>
> (I agree with Thomas that it would be good to work upon the existing
>  postcopy-test.c file, at least easier to review :)

Done.

did the other way around:

rename postcopy-test.c to migrate-test.c

and then went from there.

Later, Juan.