Messages in this thread | | | Subject | Re: [PATCH v2 0/6] RFC: gup+dma: tracking dma-pinned pages | From | Tom Talpey <> | Date | Wed, 28 Nov 2018 08:59:01 -0500 |
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On 11/27/2018 9:52 PM, John Hubbard wrote: > On 11/27/18 5:21 PM, Tom Talpey wrote: >> On 11/21/2018 5:06 PM, John Hubbard wrote: >>> On 11/21/18 8:49 AM, Tom Talpey wrote: >>>> On 11/21/2018 1:09 AM, John Hubbard wrote: >>>>> On 11/19/18 10:57 AM, Tom Talpey wrote: > [...] >>>> >>>> What I'd really like to see is to go back to the original fio parameters >>>> (1 thread, 64 iodepth) and try to get a result that gets at least close >>>> to the speced 200K IOPS of the NVMe device. There seems to be something >>>> wrong with yours, currently. >>> >>> I'll dig into what has gone wrong with the test. I see fio putting data files >>> in the right place, so the obvious "using the wrong drive" is (probably) >>> not it. Even though it really feels like that sort of thing. We'll see. >>> >>>> >>>> Then of course, the result with the patched get_user_pages, and >>>> compare whichever of IOPS or CPU% changes, and how much. >>>> >>>> If these are within a few percent, I agree it's good to go. If it's >>>> roughly 25% like the result just above, that's a rocky road. >>>> >>>> I can try this after the holiday on some basic hardware and might >>>> be able to scrounge up better. Can you post that github link? >>>> >>> >>> Here: >>> >>> git@github.com:johnhubbard/linux (branch: gup_dma_testing) >> >> I'm super-limited here this week hardware-wise and have not been able >> to try testing with the patched kernel. >> >> I was able to compare my earlier quick test with a Bionic 4.15 kernel >> (400K IOPS) against a similar 4.20rc3 kernel, and the rate dropped to >> ~_375K_ IOPS. Which I found perhaps troubling. But it was only a quick >> test, and without your change. >> > > So just to double check (again): you are running fio with these parameters, > right? > > [reader] > direct=1 > ioengine=libaio > blocksize=4096 > size=1g > numjobs=1 > rw=read > iodepth=64
Correct, I copy/pasted these directly. I also ran with size=10g because the 1g provides a really small sample set.
There was one other difference, your results indicated fio 3.3 was used. My Bionic install has fio 3.1. I don't find that relevant because our goal is to compare before/after, which I haven't done yet.
Tom.
> > > >> Say, that branch reports it has not had a commit since June 30. Is that >> the right one? What about gup_dma_for_lpc_2018? >> > > That's the right branch, but the AuthorDate for the head commit (only) somehow > got stuck in the past. I just now amended that patch with a new date and pushed > it, so the head commit now shows Nov 27: > > https://github.com/johnhubbard/linux/commits/gup_dma_testing > > > The actual code is the same, though. (It is still based on Nov 19th's f2ce1065e767 > commit.) > > > thanks, >
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