Re: [Qemu-devel] Re: [RFC] Disk integrity in QEMU

[Laurent Vivier <Laurent@lvivier.info>]

Hi,

I made some tests on my system.

Intel Xeon, 2 GB RAM
Disk SATA 80 GB, using 4 GB Partitions

my guests are:

qemu/x86_64-softmmu/qemu-system-x86_64 -hda ../victory.qcow2 -drive file=/dev/sdc1,if=virtio,cache=on -net nic,model=virtio,macaddress=52:54:00:12:34:71 -net tap -serial stdio -m 512 -nographic

qemu/x86_64-softmmu/qemu-system-x86_64 -hda ../valkyrie.qcow2 -drive file=/dev/sdc2,if=virtio,cache=on -net nic,model=virtio,macaddress=52:54:00:12:34:72 -net tap -serial stdio -m 512 -nographic

I use the fio command given by Ryan with a 5 GB dataset (bigger than
host RAM).

Results follow.


baremetal


               |  MB/s | avg sub  | avg comp |
               |       | lat (us) | lat (ms) |
---------------+-------+----------+----------+
write,16k      | 59.86 |     4.29 |    20.25 |
write,64k      | 59.87 |     7.65 |    80.99 |
write,1M       | 59.87 | 14935.89 |  1280.71 |
---------------+-------+----------+----------+
read,16k       | 59.87 |     3.98 |    20,24 |
read,64k       | 59.88 |     8.19 |    80.98 |
read,1M        | 59.85 | 14959.63 |  1280.55 |
---------------+-------+----------+----------+


one guest, cache=on

               |  MB/s | avg sub  | avg comp |
               |       | lat (us) | lat (ms) |
---------------+-------+----------+----------+
write,16k      | 59.35 |    44.64 |    20.38 |
write,64k      | 53.40 |    70.87 |    90.72 |
write,1M       | 54.81 | 18963.69 |  1395.37 |
---------------+-------+----------+----------+
read,16k       | 35.62 |     7.84 |    34.02 |
read,64k       | 34.27 |    11.86 |   141.48 |
read,1M        | 17.50 | 59689.95 |  4344.10 |
---------------+-------+----------+----------+

one guest, cache=off

               |  MB/s | avg sub  | avg comp |
               |       | lat (us) | lat (ms) |
---------------+-------+----------+----------+
write,16k      | 59.31 |     4.44 |    20.43 |
write,64k      | 14.90 |    11.54 |   325.49 |
write,1M       | 23.37 | 44683.35 |  3255.03 |
---------------+-------+----------+----------+
read,16k       | 59.00 |     4.41 |    20.54 |
read,64k       | 13.04 |    11.84 |   371.80 |
read,1M        | 17.79 | 58712.11 |  4277.20 |
---------------+-------+----------+----------+

one guest, cache=on, O_DSYNC

               |  MB/s | avg sub  | avg comp |
               |       | lat (us) | lat (ms) |
---------------+-------+----------+----------+
write,16k      | 54.44 |    13.07 |    22.25 |
write,64k      | 54.19 |    13.10 |    89.48 |
write,1M       | 58.77 | 17763.85 |  1295.22 |
---------------+-------+----------+----------+
read,16k       | 35.27 |     7.83 |    34.36 |
read,64k       | 33.59 |    11.74 |   144.36 |
read,1M        | 17.44 | 59856.18 |  4357.69 |
---------------+-------+----------+----------+

two guests, cache=on

               |  MB/s | avg sub  | avg comp |
               |       | lat (us) | lat (ms) |
---------------+-------+----------+----------+
write,16k      | 19.20 |    36.83 |    63.11 |
               | 18.90 |    35.06 |    64.10 |
write,64k      | 18.22 |    62.46 |   266.09 |
               | 17.68 |    61.64 |   274.89 |
write,1M       | 17.18 | 60442.52 |  4454.48 |
               | 17.11 | 61137.82 |  4424.15 |
---------------+-------+----------+----------+
read,16k       | 16.32 |     8.19 |    74.25 |
               | 20.62 |     7.17 |    58.77 |
read,64k       | 13.02 |    14.05 |   372.35 |
               | 13.47 |    14.60 |   359.95 |
read,1M        |  7.68 |135632.60 |  9909.40 |
               |  7.62 |137367.63 |  9985.99 |
---------------+-------+----------+----------+

two guests, cache=off

               |  MB/s | avg sub  | avg comp |
               |       | lat (us) | lat (ms) |
---------------+-------+----------+----------+
write,16k      | 26.39 |     7.08 |    45.58 |
               | 26.40 |     8.33 |    45.90 |
write,64k      |  8.08 |    12.77 |   599.79 |
               |  8.09 |    12.87 |   599.59 |
write,1M       | 10.27 |101694.60 |  7410.92 |
               | 10.28 |101513.20 |  7405.89 |
---------------+-------+----------+----------+
read,16k       | 42.36 |     4.60 |    28.60 |
               | 27.96 |    14.56 |    43.31 |
read,64k       |  5.84 |    13.31 |   830.94 |
               |  5.83 |    22.27 |   830.62 |
read,1M        |  7.82 |133631.63 |  9730.10 |
               |  7.82 |133351.59 |  9725.79 |
---------------+-------+----------+----------+

two guests, cache=on, O_DSYNC

               |  MB/s | avg sub  | avg comp |
               |       | lat (us) | lat (ms) |
---------------+-------+----------+----------+
write,16k      | 19.77 |    17.36 |    61.29 |
               | 19.73 |     6.36 |    61.43 |
write,64k      | 23.10 |    14.00 |   209.94 |
               | 36.25 |    14.51 |    25.22 |
write,1M       | 23.94 | 43704.88 |  3146.77 |
               | 36.68 | 28456.63 |  2073.53 |
---------------+-------+----------+----------+
read,16k       | 16.38 |     8.04 |    73.99 |
               | 20.08 |     6.88 |    60.38 |
read,64k       | 11.39 |    15.22 |   425.61 |
               | 11.50 |    14.97 |   421.55 |
read,1M        |  7.68 |135693.24 |  9914.71 |
               |  7.61 |137409.27 |  9984.48 |
---------------+-------+----------+----------+


-- 
------------------ Laurent.Vivier@bull.net  ------------------
"Tout ce qui est impossible reste à accomplir"    Jules Verne
"Things are only impossible until they're not" Jean-Luc Picard