From: Christoph Hellwig <hch@lst.de>
To: David Rientjes <rientjes@google.com>
Cc: Christoph Hellwig <hch@lst.de>,
Robin Murphy <robin.murphy@arm.com>,
"Lendacky, Thomas" <Thomas.Lendacky@amd.com>,
"Singh, Brijesh" <brijesh.singh@amd.com>,
"Grimm, Jon" <jon.grimm@amd.com>,
baekhw@google.com,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>
Subject: Re: [rfc] dma-mapping: preallocate unencrypted DMA atomic pool
Date: Thu, 9 Jan 2020 15:31:08 +0100 [thread overview]
Message-ID: <20200109143108.GA22656@lst.de> (raw)
In-Reply-To: <alpine.DEB.2.21.2001071152020.183706@chino.kir.corp.google.com>
On Tue, Jan 07, 2020 at 11:57:24AM -0800, David Rientjes wrote:
> I'll rely on Thomas to chime in if this doesn't make sense for the SEV
> usecase.
>
> I think the sizing of the single atomic pool needs to be determined. Our
> peak usage that we have measured from NVMe is ~1.4MB and atomic_pool is
> currently sized to 256KB by default. I'm unsure at this time if we need
> to be able to dynamically expand this pool with a kworker.
>
> Maybe when CONFIG_AMD_MEM_ENCRYPT is enabled this atomic pool should be
> sized to 2MB or so and then when it reaches half capacity we schedule some
> background work to dynamically increase it? That wouldn't be hard unless
> the pool can be rapidly depleted.
>
Note that a non-coherent architecture with the same workload would need
the same size.
> Do we want to increase the atomic pool size by default and then do
> background dynamic expansion?
For now I'd just scale with system memory size.
next prev parent reply other threads:[~2020-01-09 14:31 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-01 1:54 [rfc] dma-mapping: preallocate unencrypted DMA atomic pool David Rientjes
2020-01-06 17:34 ` Robin Murphy
2020-01-07 10:54 ` Christoph Hellwig
2020-01-07 19:57 ` David Rientjes
2020-01-09 14:31 ` Christoph Hellwig [this message]
2020-01-09 18:58 ` David Rientjes
2020-01-17 15:28 ` Tom Lendacky
2020-02-28 9:27 ` David Rientjes
2020-03-02 0:05 ` [rfc 0/6] unencrypted atomic DMA pools with dynamic expansion David Rientjes
2020-03-02 0:05 ` [rfc 1/6] dma-mapping: pass device to atomic allocation functions David Rientjes
2020-03-02 0:05 ` [rfc 2/6] dma-remap: add additional atomic pools to map to gfp mask David Rientjes
2020-03-05 15:42 ` Christoph Hellwig
2020-03-02 0:05 ` [rfc 3/6] dma-remap: wire up the atomic pools depending on " David Rientjes
2020-03-05 15:43 ` Christoph Hellwig
2020-03-02 0:05 ` [rfc 4/6] dma-remap: dynamically expanding atomic pools David Rientjes
2020-03-03 22:29 ` David Rientjes
2020-03-02 0:05 ` [rfc 5/6] dma-direct: atomic allocations must come from unencrypted pools David Rientjes
2020-03-05 15:44 ` Christoph Hellwig
2020-03-07 0:36 ` David Rientjes
2020-03-10 18:47 ` Christoph Hellwig
2020-03-02 0:05 ` [rfc 6/6] dma-remap: double the default DMA coherent pool size David Rientjes
2020-03-05 15:45 ` Christoph Hellwig
2020-04-08 21:21 ` [rfc v2 0/6] unencrypted atomic DMA pools with dynamic expansion David Rientjes
2020-04-08 21:21 ` [rfc v2 1/6] dma-remap: separate DMA atomic pools from direct remap code David Rientjes
2020-04-14 6:35 ` Christoph Hellwig
2020-04-08 21:21 ` [rfc v2 2/6] dma-pool: add additional coherent pools to map to gfp mask David Rientjes
2020-04-08 21:21 ` [rfc v2 3/6] dma-pool: dynamically expanding atomic pools David Rientjes
2020-04-08 21:21 ` [rfc v2 4/6] dma-direct: atomic allocations must come from atomic coherent pools David Rientjes
2020-04-09 21:24 ` Tom Lendacky
2020-04-14 19:18 ` David Rientjes
2020-04-14 6:43 ` Christoph Hellwig
2020-04-14 19:20 ` David Rientjes
2020-04-08 21:21 ` [rfc v2 5/6] x86/mm: unencrypted non-blocking DMA allocations use " David Rientjes
2020-04-08 21:21 ` [rfc v2 6/6] dma-pool: scale the default DMA coherent pool size with memory capacity David Rientjes
[not found] ` <20200410145520.17864-1-hdanton@sina.com>
2020-04-10 19:37 ` [rfc v2 3/6] dma-pool: dynamically expanding atomic pools David Rientjes
2020-04-14 6:44 ` Christoph Hellwig
2020-04-14 19:23 ` David Rientjes
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