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@xxxxxxxxxx: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 > 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, -- John Hubbard NVIDIA
