From: "Jonathan Lemon" <jonathan.lemon@gmail.com>
To: "Eric Dumazet" <eric.dumazet@gmail.com>
Cc: "Prout, Andrew - LLSC - MITLL" <aprout@ll.mit.edu>,
"Christoph Paasch" <christoph.paasch@gmail.com>,
"David S . Miller" <davem@davemloft.net>,
netdev <netdev@vger.kernel.org>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Jonathan Looney" <jtl@netflix.com>,
"Neal Cardwell" <ncardwell@google.com>,
"Tyler Hicks" <tyhicks@canonical.com>,
"Yuchung Cheng" <ycheng@google.com>,
"Bruce Curtis" <brucec@netflix.com>,
"Dustin Marquess" <dmarquess@apple.com>
Subject: Re: [PATCH net 2/4] tcp: tcp_fragment() should apply sane memory limits
Date: Thu, 11 Jul 2019 12:04:48 -0700 [thread overview]
Message-ID: <4B9799E0-A736-4944-9BF3-FBACCFBDCCC5@gmail.com> (raw)
In-Reply-To: <d4b1ab65-c308-382a-2a0e-9042750335e0@gmail.com>
On 11 Jul 2019, at 11:28, Eric Dumazet wrote:
> On 7/11/19 7:14 PM, Prout, Andrew - LLSC - MITLL wrote:
>>
>> In my opinion, if a small SO_SNDBUF below a certain value is no
>> longer supported, then SOCK_MIN_SNDBUF should be adjusted to reflect
>> this. The RCVBUF/SNDBUF sizes are supposed to be hints, no error is
>> returned if they are not honored. The kernel should continue to
>> function regardless of what userspace requests for their values.
>>
>
> It is supported to set whatever SO_SNDBUF value and get terrible
> performance.
>
> It always has been.
>
> The only difference is that we no longer allow an attacker to fool TCP
> stack
> and consume up to 2 GB per socket while SO_SNDBUF was set to 128 KB.
>
> The side effect is that in some cases, the workload can appear to have
> the signature of the attack.
>
> The solution is to increase your SO_SNDBUF, or even better let TCP
> stack autotune it.
> nobody forced you to set very small values for it.
I discovered we have some production services that set SO_SNDBUF to
very small values (~4k), as they are essentially doing interactive
communications, not bulk transfers. But there's a difference between
"terrible performance" and "TCP stops working".
--
Jonathan
next prev parent reply other threads:[~2019-07-11 19:04 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-17 17:03 [PATCH net 0/4] tcp: make sack processing more robust Eric Dumazet
2019-06-17 17:03 ` [PATCH net 1/4] tcp: limit payload size of sacked skbs Eric Dumazet
2019-06-17 17:14 ` Jonathan Lemon
2019-06-17 17:03 ` [PATCH net 2/4] tcp: tcp_fragment() should apply sane memory limits Eric Dumazet
2019-06-17 17:14 ` Jonathan Lemon
2019-06-18 0:18 ` Christoph Paasch
2019-06-18 2:28 ` Eric Dumazet
2019-06-18 3:19 ` Christoph Paasch
2019-06-18 3:44 ` Eric Dumazet
2019-06-18 3:53 ` Christoph Paasch
2019-06-18 4:08 ` Eric Dumazet
2019-07-10 18:23 ` Prout, Andrew - LLSC - MITLL
2019-07-10 18:28 ` Eric Dumazet
2019-07-10 18:53 ` Prout, Andrew - LLSC - MITLL
2019-07-10 19:26 ` Eric Dumazet
2019-07-11 7:28 ` Christoph Paasch
2019-07-11 9:19 ` Eric Dumazet
2019-07-11 18:26 ` Michal Kubecek
2019-07-11 18:50 ` Eric Dumazet
2019-07-11 10:18 ` Eric Dumazet
2019-07-11 17:14 ` Prout, Andrew - LLSC - MITLL
2019-07-11 18:28 ` Eric Dumazet
2019-07-11 19:04 ` Jonathan Lemon [this message]
2019-07-12 7:05 ` Eric Dumazet
2019-07-16 15:13 ` Prout, Andrew - LLSC - MITLL
2019-06-17 17:03 ` [PATCH net 3/4] tcp: add tcp_min_snd_mss sysctl Eric Dumazet
2019-06-17 17:15 ` Jonathan Lemon
2019-06-17 17:18 ` Tyler Hicks
2019-06-17 17:03 ` [PATCH net 4/4] tcp: enforce tcp_min_snd_mss in tcp_mtu_probing() Eric Dumazet
2019-06-17 17:16 ` Jonathan Lemon
2019-06-17 17:18 ` Tyler Hicks
2019-06-17 17:41 ` [PATCH net 0/4] tcp: make sack processing more robust David Miller
2019-08-02 19:02 [PATCH net 2/4] tcp: tcp_fragment() should apply sane memory limits Bernd
2019-08-02 19:14 ` Neal Cardwell
2019-08-02 19:58 ` Bernd
2019-08-14 14:41 ` Marcelo Ricardo Leitner
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