From: Christoph Hellwig <hch@infradead.org>
To: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: "Christoph Hellwig" <hch@infradead.org>,
"xdp-newbies@vger.kernel.org" <xdp-newbies@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"Christoph Hellwig" <hch@lst.de>,
"David Woodhouse" <dwmw2@infradead.org>,
"William Tu" <u9012063@gmail.com>,
"Björn Töpel" <bjorn.topel@intel.com>,
"Karlsson, Magnus" <magnus.karlsson@intel.com>,
"Alexander Duyck" <alexander.duyck@gmail.com>,
"Arnaldo Carvalho de Melo" <acme@redhat.com>
Subject: Re: XDP performance regression due to CONFIG_RETPOLINE Spectre V2
Date: Tue, 17 Apr 2018 00:13:39 -0700 [thread overview]
Message-ID: <20180417071339.GA24498@infradead.org> (raw)
In-Reply-To: <20180417090701.6b25f456@redhat.com>
On Tue, Apr 17, 2018 at 09:07:01AM +0200, Jesper Dangaard Brouer wrote:
> > > number should improve more).
> >
> > What is the number for the otherwise comparable setup without repolines?
>
> Approx 12 Mpps.
>
> You forgot to handle the dma_direct_mapping_error() case, which still
> used the retpoline in the above 8.9 Mpps measurement, I fixed it up and
> performance increased to 9.6 Mpps.
>
> Notice, in this test there are still two retpoline/indirect-calls
> left. The net_device->ndo_xdp_xmit and the invocation of the XDP BPF
> prog.
But that seems like a pretty clear indicator that we want the fast path
direct mapping. I'll try to find some time over the next weeks to
do a cleaner version of it.
prev parent reply other threads:[~2018-04-17 7:13 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-12 13:50 XDP performance regression due to CONFIG_RETPOLINE Spectre V2 Jesper Dangaard Brouer
2018-04-12 14:51 ` Christoph Hellwig
2018-04-12 14:56 ` Christoph Hellwig
2018-04-12 15:31 ` Jesper Dangaard Brouer
2018-04-13 16:49 ` Christoph Hellwig
2018-04-13 17:12 ` Tushar Dave
2018-04-13 17:26 ` Christoph Hellwig
2018-04-14 19:29 ` David Woodhouse
2018-04-16 6:02 ` Jesper Dangaard Brouer
2018-04-16 12:27 ` Christoph Hellwig
2018-04-16 16:04 ` Alexander Duyck
2018-04-17 6:19 ` Christoph Hellwig
2018-04-16 18:05 ` dma-mapping: bypass dma_ops for direct mappings kbuild test robot
2018-04-16 18:26 ` Jesper Dangaard Brouer
2018-04-16 18:31 ` kbuild test robot
2018-04-16 21:07 ` XDP performance regression due to CONFIG_RETPOLINE Spectre V2 Jesper Dangaard Brouer
2018-04-17 6:15 ` Christoph Hellwig
2018-04-17 7:07 ` Jesper Dangaard Brouer
2018-04-17 7:13 ` Christoph Hellwig [this message]
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