netdev - Re: [PATCH net-next 11/11] tcp: increase tcp

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Message-ID: <20250514205348.78733-1-kuniyu@amazon.com>
Date: Wed, 14 May 2025 13:53:39 -0700
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: <kuba@...nel.org>
CC: <bpf@...r.kernel.org>, <davem@...emloft.net>, <edumazet@...gle.com>,
	<eric.dumazet@...il.com>, <horms@...nel.org>, <jonesrick@...gle.com>,
	<kuniyu@...zon.com>, <ncardwell@...gle.com>, <netdev@...r.kernel.org>,
	<pabeni@...hat.com>, <weiwan@...gle.com>
Subject: Re: [PATCH net-next 11/11] tcp: increase tcp_rmem[2] to 32 MB

From: Jakub Kicinski <kuba@...nel.org>
Date: Wed, 14 May 2025 13:24:22 -0700
> On Tue, 13 May 2025 19:39:19 +0000 Eric Dumazet wrote:
> > Last change to tcp_rmem[2] happened in 2012, in commit b49960a05e32
> > ("tcp: change tcp_adv_win_scale and tcp_rmem[2]")
> > 
> > TCP performance on WAN is mostly limited by tcp_rmem[2] for receivers.
> > 
> > After this series improvements, it is time to increase the default.
> 
> I think this breaks the BPF syncookie test, Kuniyuki any idea why?
> 
> https://github.com/kernel-patches/bpf/actions/runs/15016644781/job/42196471693

It seems ACK was not handled by BPF at tc hook on lo.

ACK was not sent or tcp_load_headers() failed to parse it ?
both sounds unlikely though.

Will try to reproduce it.