Poor disk performance of FreeBSD under AWS

[Roger Pau Monné]

On Fri, 18 Mar 2016, Julian Elischer wrote:
> On 18/03/2016 3:00 PM, huanghwh wrote:
> > BTW, with 1G ram configuration, vi can exit very quickly.
> > At 2016-03-18 14:26:14, "huanghwh" <huanghwh at 163.com> wrote:
> > > I have a EC2 server in AWS, 4CPU+16G ram, FreeBSD 10.2R.
> > > 
> > > Use two command dd and vi:
> > > dd if=/dev/zero of=/.swap bs=1M count=8192 &
> > > 
> > > 8589934592 bytes transferred in 117.074462 secs (73371549 bytes/sec)
> > > 
> > > when dd run in background, input vi command  to edit a small txt file
> > > "d.txt" at same time,
> > > 
> > > and then write and quit immediately:
> > > 
> > > 
> > > /usr/bin/time vi d.txt
> > > 
> > > 
> > > 49.82 real 0.00 user 0.00 sys
> > > 
> > > in top command show:
> > > 810 root 1 23 0 12344K 2524K wswbuf 0 0:04 5.76% dd
> > > 821 root 1 20 0 23448K 4092K wdrain 0 0:00 0.00% vi
> > > 
> > > vi need almost 50 seconds to quit.
> I think some people are already looking at this.. it's not limited to AWS.

Is there a PR or Review about this? I don't have a 16GB system at hand, 
but it looks quite weird that it works "better" with 1GB rather than with 
16GB.

Are you using ZFS or UFS as your filesystem?

Roger.