Re: [PATCH net-next 1/2] tcp: remove per-destination timestamp cache

2017-03-19 Thread Alexander Alemayhu
On Wed, Mar 15, 2017 at 05:06:58PM -0700, Eric Dumazet wrote: > > Nat are good, Nat are good. > > I can't find this hilarious video we watched in Copenhagen ;) > Maybe 'Oops, I did it: IPv6 NAT by Patrick McHardy'[0]. Starts around 19:10. [0]: http://video.dkuug.dk/media/oops-i-did-it-ipv6-nat-

Re: [PATCH net-next 1/2] tcp: remove per-destination timestamp cache

2017-03-16 Thread Lutz Vieweg
On 03/16/2017 04:40 PM, Neal Cardwell wrote: I currently wonder: What it the correct advise to an operator who needs to run one server instance that is meant to accept thousands of new, short-lived TCP connections per minute? Note that for this to be a problem there would have to be thousands o

Re: [PATCH net-next 1/2] tcp: remove per-destination timestamp cache

2017-03-16 Thread Willy Tarreau
Hi Neal, On Thu, Mar 16, 2017 at 11:40:52AM -0400, Neal Cardwell wrote: > On Thu, Mar 16, 2017 at 7:31 AM, Lutz Vieweg wrote: > > > > On 03/15/2017 11:55 PM, Willy Tarreau wrote: > >> > >> At least I can say I've seen many people enable it without understanding > >> its impact, confusing it > >>

Re: [PATCH net-next 1/2] tcp: remove per-destination timestamp cache

2017-03-16 Thread Neal Cardwell
On Thu, Mar 16, 2017 at 7:31 AM, Lutz Vieweg wrote: > > On 03/15/2017 11:55 PM, Willy Tarreau wrote: >> >> At least I can say I've seen many people enable it without understanding its >> impact, confusing it >> with tcp_tw_reuse, and copy-pasting it from random blogs and complaining >> about iss

Re: [PATCH net-next 1/2] tcp: remove per-destination timestamp cache

2017-03-16 Thread Lutz Vieweg
On 03/15/2017 11:55 PM, Willy Tarreau wrote: At least I can say I've seen many people enable it without understanding its impact, confusing it with tcp_tw_reuse, and copy-pasting it from random blogs and complaining about issues in production. I currently wonder: What it the correct advise to

Re: [PATCH net-next 1/2] tcp: remove per-destination timestamp cache

2017-03-15 Thread Eric Dumazet
On Wed, 2017-03-15 at 16:45 -0700, David Miller wrote: > Ok, I guess we can remove it in that case. I'm still a bit disappointed > as I was always hoping someone would find a way to make this work even > in the presence of NAT. Nat are good, Nat are good. I can't find this hilarious video we wa

Re: [PATCH net-next 1/2] tcp: remove per-destination timestamp cache

2017-03-15 Thread David Miller
From: Florian Westphal Date: Wed, 15 Mar 2017 23:57:26 +0100 > AFAIU we only have two alternatives, removal of the randomization feature > or switch to a offset computed via hash(saddr, daddr, secret). > > Unless there are more comments I'll look into doing the latter tomorrow. No, I'll apply t

Re: [PATCH net-next 1/2] tcp: remove per-destination timestamp cache

2017-03-15 Thread David Miller
From: Eric Dumazet Date: Wed, 15 Mar 2017 15:59:01 -0700 > On Wed, 2017-03-15 at 15:40 -0700, David Miller wrote: >> From: Soheil Hassas Yeganeh >> Date: Wed, 15 Mar 2017 16:30:45 -0400 >> >> > Note that this cache was already broken for caching timestamps of >> > multiple machines behind a NAT

Re: [PATCH net-next 1/2] tcp: remove per-destination timestamp cache

2017-03-15 Thread Eric Dumazet
On Wed, 2017-03-15 at 15:40 -0700, David Miller wrote: > From: Soheil Hassas Yeganeh > Date: Wed, 15 Mar 2017 16:30:45 -0400 > > > Note that this cache was already broken for caching timestamps of > > multiple machines behind a NAT sharing the same address. > > That's the documented, well establ

Re: [PATCH net-next 1/2] tcp: remove per-destination timestamp cache

2017-03-15 Thread Florian Westphal
David Miller wrote: > From: Soheil Hassas Yeganeh > Date: Wed, 15 Mar 2017 16:30:45 -0400 > > > Note that this cache was already broken for caching timestamps of > > multiple machines behind a NAT sharing the same address. > > That's the documented, well established, limitation of time-wait > r

Re: [PATCH net-next 1/2] tcp: remove per-destination timestamp cache

2017-03-15 Thread Willy Tarreau
Hi David, On Wed, Mar 15, 2017 at 03:40:44PM -0700, David Miller wrote: > From: Soheil Hassas Yeganeh > Date: Wed, 15 Mar 2017 16:30:45 -0400 > > > Note that this cache was already broken for caching timestamps of > > multiple machines behind a NAT sharing the same address. > > That's the docum

Re: [PATCH net-next 1/2] tcp: remove per-destination timestamp cache

2017-03-15 Thread David Miller
From: Soheil Hassas Yeganeh Date: Wed, 15 Mar 2017 16:30:45 -0400 > Note that this cache was already broken for caching timestamps of > multiple machines behind a NAT sharing the same address. That's the documented, well established, limitation of time-wait recycling. People who enable it, need