Re: [PATCH net-next 00/10] net: faster and simpler CRC32C computation

Ard Biesheuvel
2025-05-11T21:45:27Z

On Sun, 11 May 2025 at 23:22, Andrew Lunn <andrew@lunn.ch> wrote:
>
> On Sun, May 11, 2025 at 10:29:29AM -0700, Eric Biggers wrote:
> > On Sun, May 11, 2025 at 06:30:25PM +0200, Andrew Lunn wrote:
> > > On Sat, May 10, 2025 at 05:41:00PM -0700, Eric Biggers wrote:
> > > > Update networking code that computes the CRC32C of packets to just call
> > > > crc32c() without unnecessary abstraction layers. The result is faster
> > > > and simpler code.
> > >
> > > Hi Eric
> > >
> > > Do you have some benchmarks for these changes?
> > >
> > > Andrew
> >
> > Do you want benchmarks that show that removing the indirect calls makes things
> > faster? I think that should be fairly self-evident by now after dealing with
> > retpoline for years, but I can provide more details if you need them.
>
> I was think more like iperf before/after? Show the CPU load has gone
> down without the bandwidth also going down.
>
> Eric Dumazet has a T-Shirt with a commit message on the back which
> increased network performance by X%. At the moment, there is nothing
> T-Shirt quotable here.
>

I think that removing layers of redundant code to ultimately call the
same core CRC-32 implementation is a rather obvious win, especially
when indirect calls are involved. The diffstat speaks for itself, so
maybe you can print that on a T-shirt.