Date: Fri, 5 Jan 2018 09:28:18 -0800 From: Matt Joras <mjoras@freebsd.org> To: Steven Hartland <steven@multiplay.co.uk> Cc: Eugene Grosbein <eugen@grosbein.net>, src-committers <src-committers@freebsd.org>, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r327559 - in head: . sys/net Message-ID: <CADdTf%2Bi47-X1HVb=JBFi53wOgbX1x1euHr53-YyqNDDFNF9PLw@mail.gmail.com> In-Reply-To: <97d173fb-4f47-609d-8319-07282a283473@multiplay.co.uk> References: <201801042005.w04K5liB049411@repo.freebsd.org> <5A4E9397.9000308@grosbein.net> <f133b587-1f7e-4594-31d1-974775ad55be@freebsd.org> <5A4EDC62.50508@grosbein.net> <c42bfb9e-e583-aca3-bf0d-4d92c0153d2f@multiplay.co.uk> <5A4F824C.1060405@grosbein.net> <97d173fb-4f47-609d-8319-07282a283473@multiplay.co.uk>
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On Fri, Jan 5, 2018 at 7:42 AM, Steven Hartland <steven@multiplay.co.uk> wrote: > My current thinking is that flowid shouldn't be used for either LACP or > loadbalance protocols as doing so will almost certainly lead to unexpected > behavior (the stated lagghash may not be valid). > > Regards > Steve > For what it's worth, this was the conclusion I came to, and at Isilon we've made the same change being discussed here. For the case of drivers that end up using a queue index for the flowid, you end up with pathological behavior on the lagg; the flowid ends up getting right shifted by (default) 16. So in the case of e.g. two bxe(4) interfaces with 4 queues, you always end up choosing the interface in the lagg at index 0. This was enough to make us completely disable it. Customers started noticing when they upgraded from the BSD7-based release (which predates flowid) to the BSD10-based release. It is my impression that this sort of situation is probably more common in FreeBSD, especially since some drivers only set the flowid to an RSS hash when RSS is defined, otherwise defaulting to a queue index. Matt
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