Date: Mon, 3 Oct 2011 01:20:44 -0700 From: Jack Vogel <jfvogel@gmail.com> To: Hooman Fazaeli <fazaeli@sepehrs.com> Cc: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org> Subject: Re: em(4) high latency w/o msix Message-ID: <CAFOYbckcT3H4%2BU=-anhA0jUpQRE6vQDgr31H8MQn%2BOVy%2BTw%2B6Q@mail.gmail.com> In-Reply-To: <4E896999.3020001@sepehrs.com> References: <4E886A3B.7000502@sepehrs.com> <CAFOYbcnUbdrCYyDdSeYOWVNL_vhH_zA1d5B=mgrkoUijHXj-SQ@mail.gmail.com> <4E896999.3020001@sepehrs.com>
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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> 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>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: icmp_seq=0 ttl=64 time=0.055 ms >> 64 bytes from 192.168.1.83: icmp_seq=1 ttl=64 time=0.076 ms >> 64 bytes from 192.168.1.83: icmp_seq=2 ttl=64 time=0.066 ms >> 64 bytes from 192.168.1.83: icmp_seq=3 ttl=64 time=0.051 ms >> 64 bytes from 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: icmp_seq=0 ttl=64 time=0.180 ms >> 64 bytes from 192.168.1.83: icmp_seq=1 ttl=64 time=0.164 ms >> 64 bytes from 192.168.1.83: icmp_seq=2 ttl=64 time=0.169 ms >> 64 bytes from 192.168.1.83: icmp_seq=3 ttl=64 time=0.172 ms >> 64 bytes from 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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