Messages in this thread |  | | Date | Thu, 9 Jan 2020 15:31:08 +0100 | From | Christoph Hellwig <> | Subject | Re: [rfc] dma-mapping: preallocate unencrypted DMA atomic pool |
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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.
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