From: Will Deacon <will.deacon@arm.com>
To: Zhangshaokun <zhangshaokun@hisilicon.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>,
steve.capper@arm.com, netdev@vger.kernel.org,
ilias.apalodimas@linaro.org,
"huanglingyan \(A\)" <huanglingyan2@huawei.com>,
robin.murphy@arm.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] arm64: do_csum: implement accelerated scalar version
Date: Fri, 12 Apr 2019 10:52:43 +0100 [thread overview]
Message-ID: <20190412095243.GA27193@fuggles.cambridge.arm.com> (raw)
In-Reply-To: <d7a16ebd-073f-f50e-9651-68606d10b01c@hisilicon.com>
On Fri, Apr 12, 2019 at 10:31:16AM +0800, Zhangshaokun wrote:
> On 2019/2/19 7:08, Ard Biesheuvel wrote:
> > It turns out that the IP checksumming code is still exercised often,
> > even though one might expect that modern NICs with checksum offload
> > have no use for it. However, as Lingyan points out, there are
> > combinations of features where the network stack may still fall back
> > to software checksumming, and so it makes sense to provide an
> > optimized implementation in software as well.
> >
> > So provide an implementation of do_csum() in scalar assembler, which,
> > unlike C, gives direct access to the carry flag, making the code run
> > substantially faster. The routine uses overlapping 64 byte loads for
> > all input size > 64 bytes, in order to reduce the number of branches
> > and improve performance on cores with deep pipelines.
> >
> > On Cortex-A57, this implementation is on par with Lingyan's NEON
> > implementation, and roughly 7x as fast as the generic C code.
> >
> > Cc: "huanglingyan (A)" <huanglingyan2@huawei.com>
> > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> > ---
> > Test code after the patch.
>
> Hi maintainers and Ard,
>
> Any update on it?
I'm waiting for Robin to come back with numbers for a C implementation.
Robin -- did you get anywhere with that?
Will
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next prev parent reply other threads:[~2019-04-12 9:53 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-18 23:08 [PATCH] arm64: do_csum: implement accelerated scalar version Ard Biesheuvel
2019-02-19 15:08 ` Ilias Apalodimas
2019-02-28 14:16 ` Ard Biesheuvel
2019-02-28 15:13 ` Robin Murphy
2019-02-28 15:28 ` Ard Biesheuvel
2019-04-12 2:31 ` Zhangshaokun
2019-04-12 9:52 ` Will Deacon [this message]
2019-04-15 18:18 ` Robin Murphy
2019-05-15 9:47 ` Will Deacon
2019-05-15 10:15 ` David Laight
2019-05-15 10:57 ` Robin Murphy
2019-05-15 11:13 ` David Laight
2019-05-15 12:39 ` Robin Murphy
2019-05-15 13:54 ` David Laight
2019-05-15 11:02 ` Robin Murphy
2019-05-16 3:14 ` Zhangshaokun
2019-08-15 16:46 ` Will Deacon
2019-08-16 8:15 ` Shaokun Zhang
2019-08-16 14:55 ` Robin Murphy
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