Re: [Qemu-block] [PATCH v2] mirror: double performance of the bulk stage if the disc is full

[Kevin Wolf]

Am 14.07.2016 um 19:19 hat Vladimir Sementsov-Ogievskiy geschrieben:
> Mirror can do up to 16 in-flight requests, but actually on full copy
> (the whole source disk is non-zero) in-flight is always 1. This happens
> as the request is not limited in size: the data occupies maximum available
> capacity of s->buf.
> 
> The patch limits the size of the request to some artificial constant
> (1 Mb here), which is not that big or small. This effectively enables
> back parallelism in mirror code as it was designed.
> 
> The result is important: the time to migrate 10 Gb disk is reduced from
> ~350 sec to 170 sec.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> Signed-off-by: Denis V. Lunev <address@hidden>

This broke qemu-iotests 109 for raw. Can you please check whether the
output changes are expected, and send a fix either for the code or for
the test case?

Kevin