Messages in this thread | | | Date | Thu, 28 Apr 2022 17:06:44 +0200 | From | Christoph Hellwig <> | Subject | Re: [PATCH] nvme-pci: fix host memory buffer allocation size |
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On Thu, Apr 28, 2022 at 04:44:47PM +0200, Thomas Weißschuh wrote: > Is the current code supposed to reach HMPRE? It does not for me. > > The code tries to allocate memory for HMPRE in chunks. > The best allocation would be to allocate one chunk for all of HMPRE. > If this fails we half the chunk size on each iteration and try again. > > On my hardware we start with a chunk_size of 4MiB and just allocate > 8 (hmmaxd) * 4 = 32 MiB which is worse than 1 * 200MiB.
And that is because the hardware only has a limited set of descriptors.
Is there any real problem you are fixing with this? Do you actually see a performance difference on a relevant workload?
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