Date: Thu, 8 Aug 2024 09:02:33 +0800 From: Zhenlei Huang <zlei@FreeBSD.org> To: Alan Somers <asomers@freebsd.org> Cc: FreeBSD Net <freebsd-net@freebsd.org> Subject: Re: Monitoring packet loss Message-ID: <FAB4E19F-F0A2-408A-A927-10D98960D829@FreeBSD.org> In-Reply-To: <CAOtMX2hLaYEhVpoPG5HtJ7Qj030PvGOBFeo78fqmRxPMJAfxmQ@mail.gmail.com> References: <CAOtMX2hLaYEhVpoPG5HtJ7Qj030PvGOBFeo78fqmRxPMJAfxmQ@mail.gmail.com>
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> On Aug 7, 2024, at 10:06 PM, Alan Somers <asomers@freebsd.org> wrote: >=20 > I'd like to track the rate of packet loss for outbound packets from > some production servers. Obviously, that's impossible. =20 Can `netstat -di` fulfill ? The column `Oerrs` and `Drop` ( this is the out dropped packets ) may be = what you want. The drivers also expose some internal stats via sysctl. But different = drivers vary. For example cxgbe(4) ``` # sysctl dev.cxl.0.stats.tx_drop ``` Best regards, Zhenlei > But I think > that the rate of TCP retransmissions should be a close proxy for > packet loss. Currently I can only observe TCP retransmissions by > using wireshark, a slow and laborious process. But it seems to me > that the network stack should already have that information. Would it > be possible to add a sysctl to expose the total number of > retransmissions since boot? This information would be very useful. > It could reveal for example problems with a model of NIC, or > congestion on one network segment but not another, or a regression in > the OS. >=20 > -Alan >=20
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