Date: Tue, 04 Oct 2011 15:06:37 +0330 From: Hooman Fazaeli <hoomanfazaeli@gmail.com> To: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>, Jack Vogel <jfvogel@gmail.com> Subject: Re: em(4) high latency w/o msix Message-ID: <4E8AEFC5.8050103@gmail.com>
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8.2-RELEASE and stable/8 have the same problem. Ping RTT triples when MSIX is disabled. On 10/3/2011 11:50 AM, Jack Vogel wrote: > Can you try the driver in 8.2 and possibly stable/8 to see the behavior there. > > And, just curious, why are you disabling MSIX? > > Jack > > > On Mon, Oct 3, 2011 at 12:51 AM, Hooman Fazaeli <fazaeli@sepehrs.com <mailto:fazaeli@sepehrs.com>> wrote: > > Hi Jack > > The hardware is a PCIe network appliance with 3 port modules. The ports I have > used in the test are 82574L residing on a 4 port module. Anyway, as I noted > in last mail, the stock 7.3-RELEASE driver does not expose this problem on > the same hardware. > > > On 10/2/2011 7:38 PM, Jack Vogel wrote: >> On what hardware? >> >> Jack >> >> >> On Sun, Oct 2, 2011 at 6:42 AM, Hooman Fazaeli <fazaeli@sepehrs.com <mailto:fazaeli@sepehrs.com>> wrote: >> >> >> Latest em(4) driver from HEAD seems to have high latency >> when MSIX is disabled. >> >> With MSIX enabled (hw.em.enable_msix=1): >> >> # ping -c5 192.168.1.83 >> PING 192.168.1.83 (192.168.1.83): 56 data bytes >> 64 bytes from 192.168.1.83 <http://192.168.1.83>: icmp_seq=0 ttl=64 time=0.055 ms >> 64 bytes from 192.168.1.83 <http://192.168.1.83>: icmp_seq=1 ttl=64 time=0.076 ms >> 64 bytes from 192.168.1.83 <http://192.168.1.83>: icmp_seq=2 ttl=64 time=0.066 ms >> 64 bytes from 192.168.1.83 <http://192.168.1.83>: icmp_seq=3 ttl=64 time=0.051 ms >> 64 bytes from 192.168.1.83 <http://192.168.1.83>: icmp_seq=4 ttl=64 time=0.063 ms >> >> --- 192.168.1.83 ping statistics --- >> 5 packets transmitted, 5 packets received, 0.0% packet loss >> round-trip min/avg/max/stddev = 0.051/0.062/0.076/0.009 ms >> >> With MSIX disabled: >> >> # ping -c5 192.168.1.83 >> PING 192.168.1.83 (192.168.1.83): 56 data bytes >> 64 bytes from 192.168.1.83 <http://192.168.1.83>: icmp_seq=0 ttl=64 time=0.180 ms >> 64 bytes from 192.168.1.83 <http://192.168.1.83>: icmp_seq=1 ttl=64 time=0.164 ms >> 64 bytes from 192.168.1.83 <http://192.168.1.83>: icmp_seq=2 ttl=64 time=0.169 ms >> 64 bytes from 192.168.1.83 <http://192.168.1.83>: icmp_seq=3 ttl=64 time=0.172 ms >> 64 bytes from 192.168.1.83 <http://192.168.1.83>: icmp_seq=4 ttl=64 time=0.167 ms >> >> --- 192.168.1.83 ping statistics --- >> 5 packets transmitted, 5 packets received, 0.0% packet loss >> round-trip min/avg/max/stddev = 0.164/0.170/0.180/0.005 ms >> >> As you see, w/o MSIX, RTT increases by a factor of 3. >> >> I also tested the following drivers: >> - igb(4) from HEAD: OK. >> - Stock 7.3-RELEASE: OK. >> - Stock 7.4-RELEASE: problem exist. >> >> Any ideas? >> >> >> >> >> >
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