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Description of problem:

Exec migration is very slow (writes at the speed of 1.5MB/s on my hardware).

Version-Release number of selected component (if applicable):

All.

How reproducible:
Allways.

Steps to Reproduce:
1. start qemu
2. migrate in command line with something like:
   migrate -d "exec: dd of=/tmp/kkk"
3.
  
Actual results:

very low write speed (~1MB/s)

Expected results:

fastest write (~30MB/s at least)

Additional info:

Problem is that code is using double buffering (using FILE on top of QEMUFile abstraction).  With a hack to change fwrite() to write() speeds got back to normal.  Will fix things properly.

Real problem is that the small pipe buffers fill up easily, and QEMUFileBuffered clams up until 100 ms pass.

Fix is to let migration know we're ready when the pipes come back.

Verified in qemu-kvm-0.12.1.2-2.96.el6 ,Reproduced in Reproduce in qemu-kvm-0.12.1.2-2.94.el6

Steps:
1. start qemu-kvm
2. {"execute":"migrate","arguments":{"uri":"dd of=/home/tt"}}

Actual Results:
the write speed is 18MB/s ,the read speed is 91Mb/s

The bug has already been fixed.

According to comment #8 ,close this issue.

*** Bug 591366 has been marked as a duplicate of this bug. ***