Messages in this thread | | | Date | Wed, 30 May 2018 06:52:04 +0200 | From | Joerg Roedel <> | Subject | Re: [PATCH] iommu/amd - Optimize PPR log handling |
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On Tue, May 29, 2018 at 12:28:54PM -0500, Gary R Hook wrote: > No, no numbers. We're still working out how best to test this, and > suggestions/strategies are welcome.
Maybe run a simple kernel on the CPU that does a memcpy on a larger portion of mmapped (but yet unmapped) process address space and measure the time it takes for the kernel to run. The page-fault path in the iommu-driver is only a small part of the involved code here, but maybe you already see a difference. Doing a u-benchmark only for that code is probably a bit more challenging.
> The change is modeled after the function iommu_poll_events(), which is much > cleaner. The GA log handling should be changed, as well (there are > superfluous writes in the loop), but I figured, "one thing at a time". This > is admittedly a minor optimization, but discussions with Tom Lendacky have > led us down this path. > > Your feedback is appreciated.
Yeah, the patch looks good to me from my first review. But since I can't test that code myself I was wondering if you did any tests and can share something with me to run my own tests :)
Joerg
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