Re: [PATCH 0/2] Increase amount of data for monitor to read

[Vladimir Sementsov-Ogievskiy]

09.11.2020 11:50, Vladimir Sementsov-Ogievskiy wrote:
> 06.11.2020 15:42, Andrey Shinkevich wrote:
> > The subject was discussed here:
> > https://lists.gnu.org/archive/html/qemu-devel/2017-05/msg00206.html
> >
> > This series is a solution for the issue with QMP monitor buffered input.
> > A little parser is introduced to throttle JSON commands read from the
> > buffer so that QMP requests do not overwhelm the monitor input queue.
> > A side effect raised in the test #247 was managed in the first patch.
> > It may be considered as a workaround. Any sane fix suggested will be
> > appreciated.
> >
> > Note:
> > This series goes after the Vladimir's one:
> > '[PATCH v3 00/25] backup performance: block_status + async"'
> > To make the test #129 passed, the following patch should be applied first:
> > '[PATCH v3 01/25] iotests: 129 don't check backup "busy"'.
>
> Hi!
>
> I tried the following test:
>
> start qemu:
>
>    ./qemu-system-x86_64 -qmp stdio
>
> type the following in one line:
>
>    { 'execute': 'qmp_capabilities' }{ 'execute': 'quit' }
>
> press Enter.
>
> Without your patches, the qemu quits immediately, printing double "{"return": 
> {}}".
> With your patches applied qemu prints "{"return": {}}" only once and doesn't 
> quit, until I press Enter the second time.


Positive thing: the patches do increase performance:

for me, the following command:

(echo "{ 'execute': 'qmp_capabilities' }"; for i in {1..10000}; do echo "{ 'execute': 
'query-block-jobs' }"; done; echo "{ 'execute': 'quit' }" ) | time ./qemu-system-x86_64 -qmp 
stdio > /dev/null

shows 2.4s on master and 0.6s after patches


> > Andrey Shinkevich (2):
> >    iotests: add another bash sleep command to 247
> >    monitor: increase amount of data for monitor to read
> >
> >   chardev/char-fd.c          | 64 +++++++++++++++++++++++++++++++++++++++++++++-
> >   chardev/char-socket.c      | 54 +++++++++++++++++++++++++++-----------
> >   chardev/char.c             | 40 +++++++++++++++++++++++++++++
> >   include/chardev/char.h     | 15 +++++++++++
> >   monitor/monitor.c          |  2 +-
> >   tests/qemu-iotests/247     |  2 ++
> >   tests/qemu-iotests/247.out |  1 +
> >   7 files changed, 161 insertions(+), 17 deletions(-)


--
Best regards,
Vladimir