Abysmally slow write to geom class volume over network

[Michael Osipov]

Am 2016-10-14 um 11:43 schrieb Fabian Keil:
> Michael Osipov <1983-01-06 at gmx.net> wrote:
>
>> Am 2016-10-13 um 03:41 schrieb John-Mark Gurney:
>>> Michael Osipov wrote this message on Wed, Oct 12, 2016 at 20:54
>>> +0200:
>>>> As if there is a bottleneck between socket read and geom write to FS.
>>>>
>>>> Is that better?
>>>
>>> Have you run gstat on the system to see if there is an IO bottle
>>> neck?  Since you are using graid3, you want to look to see if
>>> it's %busy is ~100, while the underlying components are not.
>>
>> This is hardly impossible because as soon as I start some SFTP transfer,
>> all of my SSH sessions free or receive connetion timeout/abort.  Doing a
>> SFTP from FreeBSD to FreeBSD gives me on both physical disks and RAID3
>> volume a busy of zero to one perfect. In other terms, the drives are
>> bored.
>
> Try checking the FAIL and SLEEP columns in the "vmstat -z" output.

I assume that you expect a rise on those numbers. I have made several 
runs. Rebooted the machine and then started SFTP transfer. After seconds 
my SSH sessions locked up. The transfer was aborted manually after 10 
minutes which should have saturated the entire connection. After that, I 
reran vmstat -z, no or minimal rise in FAIL and SLEEP.

Interesting to say that this happens if is is a UFS volume on 
gconcat/graid3/gvinum/gstripe configuration. Regular gpart with GPT has 
no performance penalty. Additionally, it is not limited to SSH but 
virtually everything with sockets: nc, ggate, smb.

> This could be related to:
> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=209680#c2

It pretty much sounds like it, though I do not use ipfw, pf or any NAT 
stuff. I will try your first patch and let you know.

Do you want me to add my usecase to the issue?

Michael