From: Thomas Graf <tgraf@suug.ch>
To: Tom Herbert <tom@herbertland.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Linux Kernel Network Developers <netdev@vger.kernel.org>,
Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH net-next 1/2] net: Set sk_txhash from a random number
Date: Wed, 29 Jul 2015 22:02:30 +0200 [thread overview]
Message-ID: <20150729200230.GB26146@pox.localdomain> (raw)
In-Reply-To: <CALx6S35Y+XsHHKNDkYzyYgbNH3tv4po-ix3GAhrpawbgg2LBXA@mail.gmail.com>
On 07/29/15 at 08:58am, Tom Herbert wrote:
> The salient property of both sk_txhash and skb->hash is that they
> provide a uniform distribution over flows. It is incorrect to assume
> that either of these immutable during the lifetime of a flow, so yes
> this means that packets of a flow may go to different receive queues
> when hashes change. SO_REUSEPORT is a process in the receive path but
> uses ehashfn over the ports. But even with SO_REUSEPORT we provide no
> guarantee that packets of a "flow" will always hit the same socket,
> the hashing is not consistent when new reuseport sockets are added or
> removed-- this is actually a long standing issue with SO_REUSEPORT in
> the TCP case since it is possible to orphan connections in SYN-RECV. I
> believe Eric was working toward fixing that, so maybe in the future we
> can use skb->hash if it is a savings.
Thanks for the explanation. I have no objections to the changes then.
next prev parent reply other threads:[~2015-07-29 20:02 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-28 23:02 [PATCH net-next 0/2] net: Initialize sk_hash to random value and reset for failing cnxs Tom Herbert
2015-07-28 23:02 ` [PATCH net-next 1/2] net: Set sk_txhash from a random number Tom Herbert
2015-07-29 9:13 ` Thomas Graf
2015-07-29 9:29 ` Eric Dumazet
2015-07-29 9:54 ` Thomas Graf
2015-07-29 10:06 ` Eric Dumazet
2015-07-29 10:47 ` Thomas Graf
2015-07-29 15:58 ` Tom Herbert
2015-07-29 20:02 ` Thomas Graf [this message]
2015-12-08 8:33 ` [net-next,1/2] " Alexander Drozdov
2015-12-08 13:15 ` Eric Dumazet
2015-12-08 16:33 ` Tom Herbert
2015-12-09 11:14 ` Alexander Drozdov
2015-07-28 23:02 ` [PATCH net-next 2/2] net: Recompute sk_txhash on negative routing advice Tom Herbert
2015-07-30 5:44 ` [PATCH net-next 0/2] net: Initialize sk_hash to random value and reset for failing cnxs David Miller
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