Date: Sun, 7 Jul 2013 13:17:32 +1000 From: Peter Jeremy <peter@rulingia.com> To: Hans Petter Selasky <hselasky@c2i.net> Cc: freebsd-arm@freebsd.org Subject: USB Performance on Raspberry Pi Message-ID: <20130707031732.GS39302@server.rulingia.com>
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--sdEQJo40s7ofW8iR Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi Hans, USB performance on the Raspberry Pi is rather lacking. This is important because pretty much everything goes via USB. Do you have any suggestions on how to fix the bottlenecks? I suspect one is that FreeBSD is using PIO, whereas Linux is using DMA. I've previously commented about the sawtooth pattern in ping times: 64 bytes from 192.168.123.231: icmp_seq=3D6 ttl=3D64 time=3D2.701 ms 64 bytes from 192.168.123.231: icmp_seq=3D7 ttl=3D64 time=3D1.465 ms 64 bytes from 192.168.123.231: icmp_seq=3D8 ttl=3D64 time=3D10.589 ms 64 bytes from 192.168.123.231: icmp_seq=3D9 ttl=3D64 time=3D9.688 ms 64 bytes from 192.168.123.231: icmp_seq=3D10 ttl=3D64 time=3D8.673 ms 64 bytes from 192.168.123.231: icmp_seq=3D11 ttl=3D64 time=3D7.330 ms 64 bytes from 192.168.123.231: icmp_seq=3D12 ttl=3D64 time=3D6.857 ms 64 bytes from 192.168.123.231: icmp_seq=3D13 ttl=3D64 time=3D5.946 ms 64 bytes from 192.168.123.231: icmp_seq=3D14 ttl=3D64 time=3D3.955 ms 64 bytes from 192.168.123.231: icmp_seq=3D15 ttl=3D64 time=3D2.079 ms 64 bytes from 192.168.123.231: icmp_seq=3D16 ttl=3D64 time=3D1.072 ms Whereas pinging a Linux RPi gives: round-trip min/avg/max/stddev =3D 0.276/0.373/0.455/0.049 ms yongari@ gave me same patches for the SMSC NIC but they didn't have any noticable effect. And the network throughput is also well below what Linux can achieve. If I connect an external USB disk to a Linux RPi, I get 20.6 MBps read. The same disk on FreeBSD RPi gives 6.3 MBps - with ~50% interrupt time. --=20 Peter Jeremy --sdEQJo40s7ofW8iR Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.20 (FreeBSD) iEYEARECAAYFAlHY3cwACgkQ/opHv/APuIfCeQCgnwSDmyW8bWL8IdUKIt0h2vgd StMAnRlieQOpcxqRFIWGza9bkgUc9HgC =A3BZ -----END PGP SIGNATURE----- --sdEQJo40s7ofW8iR--
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