netdev - Re: [net-next 01/12] i40e: replace switch-statement to speed-up retpoline-enabled builds

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Message-Id: <6C3E4204-AABF-45AD-B32D-62CB50391D89@appneta.com>
Date:   Mon, 29 Apr 2019 13:01:57 -0700
From:   Josh Elsasser <jelsasser@...neta.com>
To:     Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        Björn Töpel <bjorn.topel@...el.com>
Cc:     David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
        nhorman@...hat.com, sassmann@...hat.com,
        Andrew Bowers <andrewx.bowers@...el.com>
Subject: Re: [net-next 01/12] i40e: replace switch-statement to speed-up
 retpoline-enabled builds

On Apr 29, 2019, at 12:16 PM, Jeff Kirsher <jeffrey.t.kirsher@...el.com> wrote:

> From: Björn Töpel <bjorn.topel@...el.com>
> 
> GCC will generate jump tables for switch-statements with more than 5
> case statements. An entry into the jump table is an indirect call,
> which means that for CONFIG_RETPOLINE builds, this is rather
> expensive.
> 
> This commit replaces the switch-statement that acts on the XDP program
> result with an if-clause.

Apologies for the noise, but is this patch still required after the
recent threshold bump[0] and later removal[1] of switch-case jump
table generation when building with CONFIG_RETPOLINE?

[0]: https://lore.kernel.org/patchwork/patch/1044863/
[1]: https://lore.kernel.org/patchwork/patch/1054472/

If nothing else the commit message no longer seems accurate.

Regards,
-- Josh