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

[Dongsheng Song]

On Thu, Aug 22, 2013 at 5:04 PM, Sascha Wildner <saw at online.de> wrote:
> On Mon, 19 Aug 2013 09:55:12 +0200, Dongsheng Song
> <dongsheng.song at gmail.com> wrote:
>
>> Hi,
>>
>> When I running DragonFlyBSD under VMware ESXi 5.1, with the following
>> setting:
>>
>> CPUs: 8
>> Memory: 4096 MB
>> SCSI controller: LSI Logic Paraller
>> SCSI disk size: 64G
>>
>> I found this VM is very very slowly, then I check the dmesg output,
>> I'm very surprised:
>>
>> da0: 3.300MB/s transfers
>
>
> As a datapoint: I tried this morning in latest VMware Player (Windows 8
> host). While I am seeing the same weird transfer rate in dmesg (da0:
> 3.300MB/s transfers), the disk's speed looked OK to me, using the dd test
> you did (speeds were around 80MB/s).
>
> Sascha

VMware desktop disk IO have much different than ESXi. I had write a
simple program,
use O_DIRECT|O_SYNC, then these test results is stable:

16.2 ~ 18.4 MB/s       Linux
 1.4 ~ 1.8 MB/s         FreeBSD 9.1
 0.2 ~  0.4 MB/s        DFLY master

So merge mpt (LSI Logic) driver from FreeBSD is valuable, but
unfortunately, I no suck skill.

Dongsheng
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