From: Florian Fainelli <f.fainelli@gmail.com>
To: David Miller <davem@davemloft.net>, Jose.Abreu@synopsys.com
Cc: netdev@vger.kernel.org, Joao.Pinto@synopsys.com,
Vitor.Soares@synopsys.com, peppe.cavallaro@st.com,
alexandre.torgue@st.com
Subject: Re: [PATCH v2 net-next 00/12] net: stmmac: Clean-up and tune-up
Date: Wed, 16 May 2018 12:01:26 -0700 [thread overview]
Message-ID: <64edab6c-0bbf-fd8a-6be6-aaf802f6d12f@gmail.com> (raw)
In-Reply-To: <20180516.145611.65752290278287985.davem@davemloft.net>
On 05/16/2018 11:56 AM, David Miller wrote:
> From: Jose Abreu <Jose.Abreu@synopsys.com>
> Date: Wed, 16 May 2018 13:50:42 +0100
>
>> David raised some rightfull constrains about the use of indirect callbacks in
>> the code. I did iperf tests with and without patches 3-12 and the performance
>> remained equal. I guess for 1Gb/s and because my setup has a powerfull
>> processor these patches don't affect the performance.
>
> Does your cpu need Spectre v1 and v2 workarounds which cause indirect calls to
> be extremely expensive?
Given how widespread stmmac is within the ARM CPU's ecosystem, the
answer is more than likely yes.
To get a better feeling of whether your indirect branches introduce a
difference, either don't run the CPU at full speed (e.g: use cpufreq to
slow it down), and/or profile the number of cycles and instruction cache
hits/miss ratio for the functions called in hot-path.
--
Florian
next prev parent reply other threads:[~2018-05-16 19:01 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-16 12:50 [PATCH v2 net-next 00/12] net: stmmac: Clean-up and tune-up Jose Abreu
2018-05-16 12:50 ` [PATCH v2 net-next 01/12] net: stmmac: Enable OSP for GMAC4 Jose Abreu
2018-05-16 12:50 ` [PATCH v2 net-next 02/12] net: stmmac: Do not keep rearming the coalesce timer in stmmac_xmit Jose Abreu
2018-05-16 12:50 ` [PATCH v2 net-next 03/12] net: stmmac: Let descriptor code set skbuff address Jose Abreu
2018-05-16 12:50 ` [PATCH v2 net-next 04/12] net: stmmac: Let descriptor code clear the descriptor Jose Abreu
2018-05-16 12:50 ` [PATCH v2 net-next 05/12] net: stmmac: Uniformize the use of dma_{rx/tx}_mode callbacks Jose Abreu
2018-05-16 12:50 ` [PATCH v2 net-next 06/12] net: stmmac: Remove uneeded checks for GMAC version Jose Abreu
2018-05-16 12:50 ` [PATCH v2 net-next 07/12] net: stmmac: Move PTP and MMC base address calculation to hwif.c Jose Abreu
2018-05-16 12:50 ` [PATCH v2 net-next 08/12] net: stmmac: Uniformize the use of dma_init_* callbacks Jose Abreu
2018-05-16 12:50 ` [PATCH v2 net-next 09/12] net: stmmac: Remove uneeded check for GMAC version in stmmac_xmit Jose Abreu
2018-05-16 12:50 ` [PATCH v2 net-next 10/12] net: stmmac: Uniformize set_rx_owner() Jose Abreu
2018-05-16 12:50 ` [PATCH v2 net-next 11/12] net: stmmac: Let descriptor code get skbuff address Jose Abreu
2018-05-16 12:50 ` [PATCH v2 net-next 12/12] net: stmmac: Remove if condition by taking advantage of hwif return code Jose Abreu
2018-05-16 18:56 ` [PATCH v2 net-next 00/12] net: stmmac: Clean-up and tune-up David Miller
2018-05-16 19:01 ` Florian Fainelli [this message]
2018-05-17 13:24 ` Jose Abreu
2018-05-17 18:41 ` David Miller
2018-05-17 18:47 ` David Miller
2018-05-18 9:17 ` Jose Abreu
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