[Qemu-devel] [Bug 601946] Re: [Feature request] qemu-img multi-threaded compressed image conversion

[Коренберг Марк]

1. during benchmark I used iotop and just top. qemu-img is eating all my cpu 
(3.07 Ghz) and disk streaming was at low speeds.
2. Writing on disk in ext4 is cached very strongly, so writing in 4 streams is 
not the problem.
3. For example, 7z give huge speed increase in when compressing in multiple 
threads.
4. Yes, i understand, that compressing is stream-based. So we can split input 
stream by chinks and compress each chunk individually.

You can use time qemu-img convert .... and see user/system/real
timings. In my cases, user time is nearly equal real time, so CPU work
in my case is the bottleneck.

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[Feature request] qemu-img multi-threaded compressed image conversion
https://bugs.launchpad.net/bugs/601946
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Status in QEMU: New

Bug description:
Feature request:
qemu-img multi-threaded compressed image conversion

Suppose I want to convert raw image to compressed qcow2. Multi-threaded 
conversion will be much faster, because bottleneck is compressing data.