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

[Sascha Wildner]

On Sat, 24 Aug 2013 09:45:02 +0200, Dongsheng Song  
<dongsheng.song at gmail.com> wrote:

> On Sat, Aug 24, 2013 at 11:52 AM, Sascha Wildner <saw at online.de> wrote:
>> [...]
>> Could you try with this patch please?
>>
>> http://leaf.dragonflybsd.org/~swildner/cam_probe.diff
>>
>> Sascha
>
> No IO speed difference (still 0.200 ~ 0.400 MB/s with direct IO).
>
> The dmesg output just add new line:
> da0: Command Queueing Enabled

Ok, it might have been incomplete. Can you try this patch instead?

http://leaf.dragonflybsd.org/~swildner/cam_probe2.diff

It includes the first patch, so undo the first one before applying this  
one.

If that too doesn't help, can you check how many dev_openings it shows  
with 'camcontrol tags da0 -v'? mintags and maxtags give the limits. If  
dev_openings is 1, can you check if raising helps, which should work with  
'camcontrol tags da0 -N <number>', within the limits.

Sascha