Re: [Qemu-devel] [PATCH v6 0/3] High downtime with 95+ throttle pct

[Yury Kotov]

Hi,

Sorry, patchew found a leak in the auto converge test. I fixed it in v7.

Also, there are two other fails, but it seems these are not related to
my changes:

Fail 1:
https://patchew.org/logs/address@hidden/testing.docker-mingw@fedora/?type=message
...
                /tmp/qemu-test/src/qemu.nsi
File: "/tmp/qemu-test/src\README" -> no files found.
Usage: File [/nonfatal] [/a] ([/r] [/x filespec [...]] filespec [...] |
   /oname=outfile one_file_only)
Error in script "/tmp/qemu-test/src/qemu.nsi" on line 122 -- aborting creation 
process
...

Fail 2:
https://patchew.org/logs/address@hidden/testing.asan/?type=message
...
SUMMARY: AddressSanitizer: stack-use-after-scope 
/tmp/qemu-test/src/tests/test-char.c:762:50 in char_socket_server_test
...

Regards,
Yury

09.09.2019, 14:31, "Paolo Bonzini" <address@hidden>:
> On 09/09/19 12:49, Yury Kotov wrote:
>>  Hi,
>>
>>  V6:
>>  * Fix "Add qemu_cond_timedwait" patch:
>>    - Changed return type for qemu_cond_timedwait (void -> bool)
>>    - Added details in commit message
>>
>>  V5:
>>  * Updated sleep loop in throttle_thread at the suggestion of Paolo Bonzini
>>  * Fixed hanging of test
>>
>>  V4:
>>  * The test was simplified to prevent false fails.
>>
>>  V3:
>>  * Rebase fixes (migrate_set_parameter -> migrate_set_parameter_int)
>>
>>  V2:
>>  * Added a test
>>  * Fixed qemu_cond_timedwait for qsp
>>
>>  I wrote a test for migration auto converge and found out a strange thing:
>>  1. Enable auto converge
>>  2. Set max-bandwidth 1Gb/s
>>  3. Set downtime-limit 1ms
>>  4. Run standard test (just writes a byte per page)
>>  5. Wait for converge
>>  6. It's converged with 99% throttle percentage
>>  7. The result downtime was about 300-600ms <<<<
>>
>>  It's much higher than expected 1ms. I figured out that cpu_throttle_thread()
>>  function sleeps for 100ms+ for high throttle percentage (>=95%) in VCPU 
>> thread.
>>  And it sleeps even after a cpu kick.
>>
>>  Fixed it by using timedwait for ms part of sleep.
>>  E.g timedwait(halt_cond, 1ms) + usleep(500).
>
> Queued, thanks.
>
> Paolo