Why VMware Virtual disk so slow (da0: 3.300MB/s transfers) ?

[Dongsheng Song]

On Tue, Aug 20, 2013 at 9:58 AM, Justin Sherrill
<justin at shiningsilence.com> wrote:
> On Mon, Aug 19, 2013 at 3:55 AM, Dongsheng Song
> <dongsheng.song at gmail.com> wrote:
>> I found this VM is very very slowly, then I check the dmesg output,
>> I'm very surprised:
>>
>> da0: 3.300MB/s transfers
>
> This may be a capability report that's in error, rather than the
> actual speed.  Can you test the actual speed of writing to disk with
> dd or something similar?

Test on:

DragonFly v3.5.0.787.g79034-DEVELOPMENT (X86_64_GENERIC) #0: Tue Aug
20 08:58:36 CST 2013

# dd if=/dev/zero bs=8m count=128 of=/tmp/1G.img
128+0 records in
128+0 records out
1073741824 bytes transferred in 258.330393 secs (4156467 bytes/sec)

4156467 bytes/sec = 3.964 MB/s