Re: [Qemu-devel] [PATCH RFC v2 0/4] block/qapi: refactor and optimize the qmp_query_blockstats()

[Stefan Hajnoczi]

On Mon, Dec 19, 2016 at 04:51:22PM +0800, Dou Liyang wrote:
> These patches aim to refactor the qmp_query_blockstats() and
> improve the performance by reducing the running time of it.
> 
> qmp_query_blockstats() is used to monitor the blockstats, it
> querys all the graph_bdrv_states or monitor_block_backends.
> 
> There are the two jobs:
> 
> 1 For the performance:
> 
> 1.1 the time it takes(ns) in each time:
> the disk numbers     | 10    | 500
> -------------------------------------
> before these patches | 19429 | 667722 
> after these patches  | 17516 | 557044
> 
> 1.2 the I/O performance is degraded(%) during the monitor:
> 
> the disk numbers     | 10    | 500
> -------------------------------------
> before these patches | 1.3   | 14.2
> after these patches  | 0.8   | 9.1

Do you know what is consuming the remaining 9.1%?

I'm surprised to see such a high performance impact caused by a QMP
command.

Please post your QEMU command-line.

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