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Date:      Thu, 31 Aug 2023 07:55:48 +0000
From:      Wei Hu <weh@microsoft.com>
To:        Mark Millard <marklmi@yahoo.com>, Mark Saad <nonesuch@longcount.org>
Cc:        FreeBSD Hackers <freebsd-hackers@freebsd.org>
Subject:   RE: Very slow scp performance comparing to Linux [dd to /dev/null shows substantial FreeBSD vs. Ubuntu differences for bs=1k (or 1K) and bs=512]
Message-ID:  <SI2P153MB04416934796C4BC8A5A99D1CBBE5A@SI2P153MB0441.APCP153.PROD.OUTLOOK.COM>
In-Reply-To: <B84E85AB-B473-4177-8B80-03BECB8C524E@yahoo.com>
References:  <2D466F3C-527C-4EE1-8C3D-3E8CDD8D547F@yahoo.com> <543FBABC-C75A-4AB0-BFB6-1C7C15ECBA4E@longcount.org> <96A99928-4E8E-4AB1-BF3A-D026B280EC0E@yahoo.com> <SI2P153MB0441F1DBE0BB218517B0DEBABBE5A@SI2P153MB0441.APCP153.PROD.OUTLOOK.COM> <B84E85AB-B473-4177-8B80-03BECB8C524E@yahoo.com>

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> -----Original Message-----
> From: Mark Millard <marklmi@yahoo.com>
> Sent: Thursday, August 31, 2023 2:17 PM
> To: Mark Saad <nonesuch@longcount.org>
> Cc: Wei Hu <weh@microsoft.com>; FreeBSD Hackers <freebsd-
> hackers@freebsd.org>
> Subject: Re: Very slow scp performance comparing to Linux [dd to /dev/nul=
l
> shows substantial FreeBSD vs. Ubuntu differences for bs=3D1k (or 1K) and
> bs=3D512]
>=20
> On Aug 30, 2023, at 20:59, Wei Hu <weh@microsoft.com> wrote:
>=20
> >> -----Original Message-----
> >> From: Mark Millard <marklmi@yahoo.com>
> >> Sent: Thursday, August 31, 2023 10:18 AM
> >> To: Mark Saad <nonesuch@longcount.org>
> >> Cc: Wei Hu <weh@microsoft.com>; FreeBSD Hackers <freebsd-
> >> hackers@freebsd.org>
> >> Subject: Re: Very slow scp performance comparing to Linux [dd to
> >> /dev/null shows substantial FreeBSD vs. Ubuntu differences for bs=3D1k
> >> (or 1K) and bs=3D512]
> >>
> >> On Aug 30, 2023, at 18:45, Mark Saad <nonesuch@longcount.org> wrote:
> >>
> >>> All
> >>> Why not take scp out of the picture and try iperf? Why , we could be
> >>> looking
> >> at rss by default in Linux .
> >
> > Actually I did the iperf3 test as well and posted results a couple days=
 ago.
> > Pasting here:
> >
> > FreeBSD iperf3 to localhost, single stream: 30.9 Gb/s Linux iperf3 to
> > localhost, single stream: 48.8 Gb/s
>=20
> I'll note that (48.8Gb/s) / (30.9Gb/s) is a much smaller ratio than then =
either
> of the originally reported Ubuntu/FreeBSD ratios:
>=20
> (550 MB/s) / (70 MB/s)
> or:
> (350 MB/s) / (70 MB/s)
>=20
> Suggesting one or more non-network issues are contributing, especially vs=
. the
> localhost test that had the 550/70 ratio.
>=20
Yes, the network perf gap is not as big as I originally thought. Seems diff=
erent
factors contribute to the slowness of scp on FreeBSD. Network stack is only=
 one
of them.

Wei



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