Hi Anthony.
> The attached patch implements AIO support for the virtio backend so if this
> is the case, you should see the proper proportions.
First, thank you very much for making the patch.
I ran the same test program on KVM with the patch but I wasn't able to
get good results.
I checked the dm-ioband log, the I/Os didn't seem to be issued simultaneously.
It looked like the next I/O was blocked until the previous I/O was completed.
The number of issued I/Os for 60 seconds
--------------------------------------------------------------------
| device | sda11 | sda12 |
| weight setting | 80% | 20% |
|-----------+----------------+-------------------+-------------------|
| KVM AIO | I/Os | 4596 | 4728 |
| | ratio to total | 49.3% | 50.7% |
|-----------+----------------+-------------------+-------------------|
| KVM | I/Os | 5217 | 5623 |
| | ratio to total | 48.1% | 51.9% |
--------------------------------------------------------------------
Here is an another test result, which is very interesting.
I/Os were issued from a KVM virtual machine and from the host machine
simultaneously.
The number of issued I/Os for 60 seconds
--------------------------------------------------------
| issue from | Virtual Machine | Host Machine |
| device | sda11 | sda12 |
| weight setting | 80% | 20% |
|----------------+-------------------+-------------------|
| I/Os | 191 | 9466 |
| ratio to total | 2.0% | 98.0% |
--------------------------------------------------------
The most I/Os that were processed were the I/Os issued by the host machine.
There might exist another bottleneck somewhere as well.
Here is a block diagram representing the test.
+---------------------------+
| Virtual Machine |
| |
| Read/Write with O_DIRECT | +--------------------------+
| process x 128 | | Host Machine |
| | | | |
| V | | Read/Write with O_DIRECT |
| /dev/vda1 | | process x 128 |
+-------------|-------------+ +-------------|------------+
+-------------V---------------------------------V------------+
| /dev/mapper/ioband1 | /dev/mapper/ioband2 |
| 80% weight | 20% weight |
| | |
| Control I/O bandwidth according to the weights |
+-------------|---------------------------------|------------+
+-------------V-------------+ +-------------|------------+
| /dev/sda11 | | /dev/sda12 |
+---------------------------+ +--------------------------+
Thanks,
Ryo Tsuruta
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