From: Christoph Hellwig <hch@lst.de>
To: Barry Song <song.bao.hua@hisilicon.com>
Cc: catalin.marinas@arm.com, Steve Capper <steve.capper@arm.com>,
robin.murphy@arm.com, linuxarm@huawei.com,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
ganapatrao.kulkarni@cavium.com,
Andrew Morton <akpm@linux-foundation.org>,
Mike Rapoport <rppt@linux.ibm.com>,
will@kernel.org, hch@lst.de,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 1/2] dma-direct: provide the ability to reserve per-numa CMA
Date: Wed, 22 Jul 2020 16:16:58 +0200 [thread overview]
Message-ID: <20200722141658.GA17658@lst.de> (raw)
In-Reply-To: <20200628111251.19108-2-song.bao.hua@hisilicon.com>
On Sun, Jun 28, 2020 at 11:12:50PM +1200, Barry Song wrote:
> This is useful for at least two scenarios:
> 1. ARM64 smmu will get memory from local numa node, it can save its
> command queues and page tables locally. Tests show it can decrease
> dma_unmap latency at lot. For example, without this patch, smmu on
> node2 will get memory from node0 by calling dma_alloc_coherent(),
> typically, it has to wait for more than 560ns for the completion of
> CMD_SYNC in an empty command queue; with this patch, it needs 240ns
> only.
> 2. when we set iommu passthrough, drivers will get memory from CMA,
> local memory means much less latency.
I really don't like the config options. With the boot parameters
you can always hardcode that in CONFIG_CMDLINE anyway.
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next prev parent reply other threads:[~2020-07-22 14:17 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-28 11:12 [PATCH v3 0/2] make dma_alloc_coherent NUMA-aware by per-NUMA CMA Barry Song
2020-06-28 11:12 ` [PATCH v3 1/2] dma-direct: provide the ability to reserve per-numa CMA Barry Song
2020-07-22 14:16 ` Christoph Hellwig [this message]
2020-07-22 21:26 ` Song Bao Hua (Barry Song)
2020-07-23 11:55 ` Christoph Hellwig
2020-07-22 14:29 ` Christoph Hellwig
2020-07-22 21:41 ` Song Bao Hua (Barry Song)
2020-07-23 12:00 ` Christoph Hellwig
2020-07-23 12:08 ` Song Bao Hua (Barry Song)
2020-06-28 11:12 ` [PATCH v3 2/2] arm64: mm: reserve per-numa CMA to localize coherent dma buffers Barry Song
2020-07-13 2:45 ` [PATCH v3 0/2] make dma_alloc_coherent NUMA-aware by per-NUMA CMA Song Bao Hua (Barry Song)
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