RE: Very slow scp performance comparing to Linux

> -----Original Message-----
> From: Guido Falsi <mad@madpilot.net>
> Sent: Monday, August 28, 2023 6:49 PM
> To: Wei Hu <weh@microsoft.com>; Mikhail Zakharov
> <zmey20000@yahoo.com>; freebsd-hackers@freebsd.org
> Subject: Re: Very slow scp performance comparing to Linux
> 
> On 28/08/23 12:03, Wei Hu wrote:
> > Hi Mike,
> >
> > All VMs are with same type and they are in Azure. If the copy on Linux is
> being cached on the RX side, so is FreeBSD?
> >
> 
> You could perform the test using files in memory filesystems (tmpfs or the
> like). This would factor out disk performance whatever the backend.
> 
Thanks, Guido. I tried tmpfs on the RX side with both FreeBSD and Linux VMs. 
The throughput on FreeBSD went up significantly from 50 MB/s to 630 MB/s with 
NIC interface. Linux went up modestly form 550 MB/s to 660 MB/s. 

So, looks in the non-tmpfs case, the Linux ext4 filesystem does cache large amounts
of data in memory, much larger than FreeBSD ufs.

Many thanks, Mike for bringing this up and Guido, for the suggestion to try tmpfs.

Wei