RE: Very slow scp performance comparing to Linux

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?

Thanks,
Wei

> -----Original Message-----
> From: owner-freebsd-hackers@freebsd.org <owner-freebsd-
> hackers@freebsd.org> On Behalf Of Mikhail Zakharov
> Sent: Monday, August 28, 2023 4:28 PM
> To: freebsd-hackers@freebsd.org
> Subject: Re: Very slow scp performance comparing to Linux
> 
> [You don't often get email from zmey20000@yahoo.com. Learn why this is
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> 
> Hi,
> 
> What is the drive back-end of your machines? I mean, what is seem to be fast
> copied could still be cached in filesystem/storage buffers but not actually
> written on the disk.
> 
> Best,
> Mike
> 
> 
> On 8/28/2023 9:32 AM, Wei Hu wrote:
> > Hi,
> >
> > When I was testing a new NIC, I found the single stream scp performance
> was almost 8 time slower than Linux on the RX side. Initially I thought it might
> be something with the NIC. But when I switched to sending the file on
> localhost, the numbers stay the same.
> >
> > Here I was sending a 2GB file from sender to receiver using scp.  FreeBSD is a
> recent NON-DEBUG build from CURRENT. The Ubuntu Linux kernel is 6.2.0.
> Both run in HyperV VMs on the same type of hardware. The FreeBSD VM has
> 16 vcpus, while Ubuntu VM has 4 vcpu.
> >
> > Sender                Receiver        throughput
> > Linux         FreeBSD         70 MB/s
> > Linux         Linux           550 MB/s
> > FreeBSD       FreeBSD 70 MB/s
> > FreeBSD       Linux           350 MB/s
> > FreeBSD       localhost       70 MB/s
> > Linux         localhost       550 MB/s
> >
> >  From theses test, it seems I can rule out the issue on NIC and its driver.
> Looks the FreeBSD kernel network stack is much slower than Linux on single
> stream TCP, or there are some problem with scp?
> >
> > I also tried turning on following kernel parameters on FreeBSD kernel. But it
> makes no difference, neither do the other tcp cc algorithms such as htcp and
> newreno.
> >
> > net.inet.tcp.soreceive_stream="1"
> > net.isr.maxthreads="-1"
> > net.isr.bindthreads="1"
> >
> > net.inet.ip.intr_queue_maxlen=2048
> > net.inet.tcp.recvbuf_max=16777216
> > net.inet.tcp.recvspace=419430
> > net.inet.tcp.sendbuf_max=16777216
> > net.inet.tcp.sendspace=209715
> > kern.ipc.maxsockbuf=16777216
> >
> > Any ideas?
> >
> > Thanks,
> > Wei
> >