From: George Prekas <prekageo@amazon.com>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: Wenzhuo Lu <wenzhuo.lu@intel.com>,
Beilei Xing <beilei.xing@intel.com>,
Bernard Iremonger <bernard.iremonger@intel.com>, <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH] app/testpmd: fix IP checksum calculation
Date: Thu, 3 Dec 2020 10:35:50 -0600 [thread overview]
Message-ID: <56967649-1494-aacf-ce65-9df575233b86@amazon.com> (raw)
In-Reply-To: <20201203080812.3d9940c9@hermes.local>
On 12/3/2020 10:08 AM, Stephen Hemminger wrote:
> On Thu, 3 Dec 2020 07:59:54 -0600
> George Prekas <prekageo@amazon.com> wrote:
>
>> Insert a compiler barrier to make sure that the IP checksum calculation
>> happens after setting all the fields of the IP header.
>>
>> Signed-off-by: George Prekas <prekageo@amazon.com>
> I don't think this is necessary. All other OS's don't have to do this.
> The CPU is going to maintain proper memory order.
Hi Stephen,
This is not a CPU or OS issue. This is a compiler issue. The compiler is
free to reorder statements if it does not detect dependencies between
them. Without this compiler barrier, the calculated IP checksum is wrong.
next prev parent reply other threads:[~2020-12-03 16:36 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-03 13:59 George Prekas
2020-12-03 16:08 ` Stephen Hemminger
2020-12-03 16:35 ` George Prekas [this message]
2020-12-03 18:33 ` Stephen Hemminger
2020-12-04 8:59 ` Ferruh Yigit
2020-12-05 5:47 ` George Prekas
2020-12-05 5:42 ` [dpdk-dev] [PATCH v2] " George Prekas
2021-01-05 16:26 ` George Prekas
2021-01-06 18:02 ` Ferruh Yigit
2021-01-07 5:25 ` Stephen Hemminger
2021-01-07 5:39 ` George Prekas
2021-01-07 11:32 ` Ferruh Yigit
2021-01-07 13:06 ` Ferruh Yigit
2021-01-07 14:20 ` George Prekas
2021-01-07 15:22 ` Ferruh Yigit
2021-01-07 20:45 ` George Prekas
2021-01-07 15:50 ` Stephen Hemminger
2021-01-07 15:59 ` Ferruh Yigit
2021-01-07 16:29 ` Stephen Hemminger
2021-01-07 20:42 ` [dpdk-dev] [PATCH v3] " George Prekas
2021-01-18 15:20 ` Ferruh Yigit
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