From: Jesper Dangaard Brouer <brouer@redhat.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: "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>,
brouer@redhat.com
Subject: Re: XDP performance regression due to CONFIG_RETPOLINE Spectre V2
Date: Tue, 17 Apr 2018 09:07:01 +0200 [thread overview]
Message-ID: <20180417090701.6b25f456@redhat.com> (raw)
In-Reply-To: <20180417061550.GA21067@infradead.org>
On Mon, 16 Apr 2018 23:15:50 -0700
Christoph Hellwig <hch@infradead.org> wrote:
> On Mon, Apr 16, 2018 at 11:07:04PM +0200, Jesper Dangaard Brouer wrote:
> > On X86 swiotlb fallback (via get_dma_ops -> get_arch_dma_ops) to use
> > x86_swiotlb_dma_ops, instead of swiotlb_dma_ops. I also included that
> > in below fix patch.
>
> x86_swiotlb_dma_ops should not exist any mor, and x86 now uses
> dma_direct_ops. Looks like you are applying it to an old kernel :)
>
> > Performance improved to 8.9 Mpps from approx 6.5Mpps.
> >
> > (This was without my bulking for net_device->ndo_xdp_xmit, so that
> > 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.
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
next prev parent reply other threads:[~2018-04-17 7:07 UTC|newest]
Thread overview: 20+ 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 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 [this message]
2018-04-17 7:13 ` Christoph Hellwig
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