Abysmal re(4) performance under 8.1-STABLE (mid-August)

[Ulrich Spörlein]

On Mon, 08.11.2010 at 22:41:12 +0100, Ulrich Spörlein wrote:
> On Sun, 07.11.2010 at 15:10:20 -0800, Pyun YongHyeon wrote:
> > On Sun, Nov 07, 2010 at 12:24:21PM +0100, Ulrich Sp??rlein wrote:
> > > On Sat, 06.11.2010 at 23:19:33 -0700, Pyun YongHyeon wrote:
> > > > On Sat, Nov 6, 2010 at 2:37 AM, Ulrich Sp??rlein <uqs at spoerlein.net> wrote:
> > > > > Hello Pyun,
> > > > >
> > > > > On this new server, I cannot get more than ~280kByte/s up/downstream out of
> > > > > re(4) without any tweaking.
> > > > >
> > > > > re0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
> > > > > ?? ?? ?? ??options=389b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,WOL_UCAST,WOL_MCAST,WOL_MAGIC>
> > > > > ?? ?? ?? ??ether 00:21:85:63:74:34
> > > > > ?? ?? ?? ??inet6 fe80::221:85ff:fe63:7434%re0 prefixlen 64 scopeid 0x1
> > > > > ?? ?? ?? ??inet 46.4.12.147 netmask 0xffffffc0 broadcast 46.4.12.191
> > > > > ?? ?? ?? ??nd6 options=3<PERFORMNUD,ACCEPT_RTADV>
> > > > > ?? ?? ?? ??media: Ethernet autoselect (100baseTX <half-duplex>)
> > > > > ?? ?? ?? ??status: active
> > > > >
> > > > 
> > > > It seems the link was resolved to half-duplex. Does link partner
> > > > also agree on the resolved speed/duplex?
> > > 
> > > As this is a dedicated server in a colo hundreds of km away, I have no
> > > means to check this easily. Especially I cannot change the setting from
> > > auto-neg. Btw, linux will show a negotiated 100/full link via mii-tool.
> > > 
> > 
> > I guess you can contact network administrator of the data center to
> > check the switch configuration. IEEE 802.3 says if link parter use
> > forced full-duplex media and you use auto media, the resolved
> > duplex is half-duplex by definition. I think RealTek may have
> > followed the standard. There is no reason to use manual media
> > configuration unless your link partner is severely broken with
> > auto-negotiation.
> > 
> > Due to silicon bug of RealTek PHYs, rgephy(4) always use
> > auto-negotiation so manual media configuration is a kind of
> > auto-negotiation with limited set of available media advertising.
> > I don't know how Linux solve the silicon bug though. One of magic
> > DSP fixups might fix the issue, the DSP fixups vendor released is
> > not under BSD license and does not say more detailed information
> > for the code.
> 
> Luckily the provider switch me to another switch that is set to
> autoneg, instead of hardcoded to 100/full. re(4) now happily transfers
> with reasonable speeds, ie. 11MByte/s.

Alas, spoken too soon. While the throughput is now up to speed, I have
severe problems with packet loss on this device. Again, the linux rescue
system works fine, but under a recent -STABLE (including your latest
MFCs) I get an average packet loss of 10-20%. But it is not constant,
meaning every 5th packet or so, but instead will drop no packets for
minutes-hours and then blackout for 1-5 min straight (these times are
estimates, I haven't used a stop watch or anything.)

At first, putting the card into promisc mode seemed to alleviate the
issue, but the average ping packet loss during the last 10h was again up
to 10%. Due to the "blackout" nature, this drops all TCP sessions and is
really annoying.

Do you have any other ideas that I could try? Or should I simply switch
to a different hardware altogether?

Regards,
Uli