From: Christoph Hellwig <hch@lst.de>
To: Jesper Dangaard Brouer <brouer@redhat.com>
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>
Subject: Re: XDP performance regression due to CONFIG_RETPOLINE Spectre V2
Date: Thu, 12 Apr 2018 16:51:23 +0200 [thread overview]
Message-ID: <20180412145123.GA7048@lst.de> (raw)
In-Reply-To: <20180412155029.0324fe58@redhat.com>
On Thu, Apr 12, 2018 at 03:50:29PM +0200, Jesper Dangaard Brouer wrote:
> ---------------
> Implement support for keeping the DMA mapping through the XDP return
> call, to remove RX map/unmap calls. Implement bulking for XDP
> ndo_xdp_xmit and XDP return frame API. Bulking allows to perform DMA
> bulking via scatter-gatter DMA calls, XDP TX need it for DMA
> map+unmap. The driver RX DMA-sync (to CPU) per packet calls are harder
> to mitigate (via bulk technique). Ask DMA maintainer for a common
> case direct call for swiotlb DMA sync call ;-)
Why do you even end up in swiotlb code? Once you bounce buffer your
performance is toast anyway..
next prev parent reply other threads:[~2018-04-12 14:51 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 [this message]
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
2018-04-17 7:13 ` Christoph Hellwig
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