From: Christoph Hellwig <hch@infradead.org>
To: Liam Mark <lmark@codeaurora.org>
Cc: Christoph Hellwig <hch@infradead.org>,
Laura Abbott <labbott@redhat.com>,
sumit.semwal@linaro.org, arve@android.com, tkjos@android.com,
maco@android.com, joel@joelfernandes.org, christian@brauner.io,
devel@driverdev.osuosl.org, dri-devel@lists.freedesktop.org,
linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org,
afd@ti.com, john.stultz@linaro.org
Subject: Re: [PATCH 3/4] dma-buf: add support for mapping with dma mapping attributes
Date: Mon, 21 Jan 2019 13:29:47 -0800 [thread overview]
Message-ID: <20190121212947.GA28620@infradead.org> (raw)
In-Reply-To: <alpine.DEB.2.10.1901211142560.9631@lmark-linux.qualcomm.com>
On Mon, Jan 21, 2019 at 11:44:10AM -0800, Liam Mark wrote:
> The main use case is for allowing clients to pass in
> DMA_ATTR_SKIP_CPU_SYNC in order to skip the default cache maintenance
> which happens in dma_buf_map_attachment and dma_buf_unmap_attachment. In
> ION the buffers aren't usually accessed from the CPU so this allows
> clients to often avoid doing unnecessary cache maintenance.
This can't work. The cpu can still easily speculate into this area.
Moreover in general these operations should be cheap if the addresses
aren't cached.
next prev parent reply other threads:[~2019-01-21 21:29 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-18 18:37 [PATCH 0/4] ION stability and perf changes Liam Mark
2019-01-18 18:37 ` [PATCH 1/4] staging: android: ion: Support cpu access during dma_buf_detach Liam Mark
2019-01-18 19:34 ` Andrew F. Davis
2019-01-18 20:40 ` Laura Abbott
2019-01-18 18:37 ` [PATCH 2/4] staging: android: ion: Restrict cache maintenance to dma mapped memory Liam Mark
2019-01-18 20:20 ` Andrew F. Davis
2019-01-18 21:18 ` Liam Mark
2019-01-29 23:44 ` Liam Mark
2019-01-30 11:31 ` Brian Starkey
2019-02-06 15:40 ` [Linaro-mm-sig] " Ørjan Eide
2019-02-07 7:31 ` Christoph Hellwig
2019-02-07 15:45 ` Ørjan Eide
2019-02-28 23:49 ` Liam Mark
2019-01-30 14:31 ` Andrew F. Davis
2019-01-18 18:37 ` [PATCH 3/4] dma-buf: add support for mapping with dma mapping attributes Liam Mark
2019-01-18 20:48 ` Laura Abbott
2019-01-18 21:32 ` Liam Mark
2019-01-18 22:45 ` Laura Abbott
2019-01-19 10:25 ` Christoph Hellwig
2019-01-19 16:50 ` Laura Abbott
2019-01-21 8:30 ` Christoph Hellwig
2019-01-21 19:44 ` Liam Mark
2019-01-21 19:49 ` Andrew F. Davis
2019-01-21 20:20 ` Liam Mark
2019-01-21 20:24 ` Andrew F. Davis
2019-01-21 22:18 ` Liam Mark
2019-01-22 15:42 ` Andrew F. Davis
2019-01-22 22:47 ` Liam Mark
2019-01-21 21:30 ` Christoph Hellwig
2019-01-21 22:14 ` Liam Mark
2019-01-21 21:29 ` Christoph Hellwig [this message]
2019-01-21 22:12 ` Liam Mark
2019-01-22 16:06 ` Andrew F. Davis
2019-01-22 22:50 ` Liam Mark
2019-01-18 18:37 ` [PATCH 4/4] staging: android: ion: Support " Liam Mark
2019-01-21 12:19 ` Brian Starkey
2019-01-22 22:37 ` Liam Mark
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