This bug has been copied from bug #653536 and has been proposed
to be backported to 6.0 z-stream (EUS).
# time strace -o 113_4.log qemu-img convert -f qcow2 /mnt/rhel39-32.qcow2 -O qcow2 /mnt/113_4.qcow2
# grep fdatasync 113_4.log |wc -l
# time strace -o 113_5.log qemu-img convert -f qcow2 /mnt/rhel39-32.qcow2 -O qcow2 /mnt/113_5.qcow2
# grep fdatasync 113_5.log |wc -l
# /usr/libexec/qemu-kvm --help |grep cache
Based on the above, this bug is fixed.
Technical note added. If any revisions are required, please edit the "Technical Notes" field
accordingly. All revisions will be proofread by the Engineering Content Services team.
Previously, the conversion of a disk image by using the "qemu-img convert" command may have been significantly slow. With this update, various patches have been applied to improve the performance of the above command.
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.