On 8/24/20 9:33 AM, Dmitry Shulyak wrote: > On Mon, 24 Aug 2020 at 17:45, Jens Axboe <axboe@xxxxxxxxx> wrote: >> >> On 8/24/20 8:06 AM, Jens Axboe wrote: >>> On 8/24/20 5:09 AM, Dmitry Shulyak wrote: >>>> library that i am using https://github.com/dshulyak/uring >>>> It requires golang 1.14, if installed, benchmark can be run with: >>>> go test ./fs -run=xx -bench=BenchmarkReadAt/uring_8 -benchtime=1000000x >>>> go test ./fs -run=xx -bench=BenchmarkReadAt/uring_5 -benchtime=8000000x >>>> >>>> note that it will setup uring instance per cpu, with shared worker pool. >>>> it will take me too much time to implement repro in c, but in general >>>> i am simply submitting multiple concurrent >>>> read requests and watching read rate. >>> >>> I'm fine with trying your Go version, but I can into a bit of trouble: >>> >>> axboe@amd ~/g/go-uring (master)> >>> go test ./fs -run=xx -bench=BenchmarkReadAt/uring_8 -benchtime=1000000x >>> # github.com/dshulyak/uring/fixed >>> fixed/allocator.go:38:48: error: incompatible type for field 2 in struct construction (cannot use type uint64 as type syscall.Iovec_len_t) >>> 38 | iovec := []syscall.Iovec{{Base: &mem[0], Len: uint64(size)}} >>> | ^ >>> FAIL github.com/dshulyak/uring/fs [build failed] >>> FAIL >>> axboe@amd ~/g/go-uring (master)> go version >>> go version go1.14.6 gccgo (Ubuntu 10.2.0-5ubuntu1~20.04) 10.2.0 linux/amd64 >> >> Alright, got it working. What device are you running this on? And am I >> correct in assuming you get short reads, or rather 0 reads? What file >> system? > > Was going to look into this. > I am getting 0 reads. This is on some old kingston ssd, ext4. I can't seem to reproduce this. I do see some cqe->res == 0 completes, but those appear to be NOPs. And they trigger at the start and end. I'll keep poking. -- Jens Axboe
