hi, (thanks for having a look at this)
On Tue, Oct 17, 2017 at 6:01 AM, mura <arumaka...@gmail.com> wrote: > Hi, > > A sequential read with `dd if=f64s.root of=/dev/null bs=32` takes around > 8.5 secs (10.4 secs using read-data.go) on my machine. It would even take > up to 55 secs when bs = 1. > Also I observe that the MaxRSS of the C++ program is much bigger than the > Go version, so I suspect the C++ program probably does some kind of caching > or preloading. > most of that extra RSS is coming from the C++ libraries that are linked against. that said, it's true the C++ version does both caching and prefetching. I am trying to devise a test case where both are disabled. but, if I were to ioutil.ReadFile("foo.root") and then use that []byte slice as input (implementing all the io.Reader, io.ReaderAt ... needed interfaces) I should be able to at least recoup the caching effect, right? (that's in effect pretty much the same thing than mmap-ing the whole in memory, isn't?) -s > > -mura > > > On Monday, October 16, 2017 at 11:53:56 PM UTC+8, Sebastien Binet wrote: >> >> hi there, >> >> I have this Go program that reads a binary file format coming from CERN. >> I am trying to get it running almost as fast as its C++ counter-part. >> >> the profile and code are here: >> - https://cern.ch/binet/go-hep/rootio.cpu.pprof >> - https://cern.ch/binet/go-hep/read-data.go >> >> on my machine, I get the following timings for the C++ (g++-7.2.0) and >> the Go-1.9.1 programs: >> >> === C++/ROOT === >> real=6.84 user=6.29 sys=0.52 CPU=99% MaxRSS=258384 I/O=0/0 >> real=6.99 user=6.42 sys=0.55 CPU=99% MaxRSS=258312 I/O=0/0 >> real=6.68 user=6.12 sys=0.55 CPU=99% MaxRSS=257956 I/O=0/0 >> real=6.88 user=6.33 sys=0.54 CPU=99% MaxRSS=258964 I/O=0/0 >> real=6.87 user=6.30 sys=0.56 CPU=99% MaxRSS=258024 I/O=0/0 >> real=6.89 user=6.32 sys=0.56 CPU=99% MaxRSS=260452 I/O=0/0 >> real=6.70 user=6.14 sys=0.56 CPU=99% MaxRSS=258368 I/O=0/0 >> real=7.02 user=6.47 sys=0.54 CPU=99% MaxRSS=258128 I/O=0/0 >> real=7.46 user=6.44 sys=0.56 CPU=93% MaxRSS=257972 I/O=1840/0 >> real=7.11 user=6.47 sys=0.55 CPU=98% MaxRSS=258148 I/O=3984/0 >> >> === go-hep/rootio === >> real=13.06 user=12.43 sys=0.61 CPU=99% MaxRSS=40864 I/O=0/0 >> real=13.05 user=12.46 sys=0.58 CPU=100% MaxRSS=40892 I/O=0/0 >> real=13.05 user=12.46 sys=0.59 CPU=100% MaxRSS=40888 I/O=0/0 >> real=13.07 user=12.48 sys=0.58 CPU=99% MaxRSS=40940 I/O=0/0 >> real=13.08 user=12.48 sys=0.60 CPU=100% MaxRSS=40924 I/O=0/0 >> real=13.09 user=12.46 sys=0.60 CPU=99% MaxRSS=40976 I/O=0/0 >> real=13.01 user=12.41 sys=0.60 CPU=100% MaxRSS=40876 I/O=0/0 >> real=13.09 user=12.52 sys=0.58 CPU=100% MaxRSS=40880 I/O=0/0 >> real=13.01 user=12.41 sys=0.60 CPU=100% MaxRSS=40880 I/O=0/0 >> real=12.99 user=12.41 sys=0.58 CPU=100% MaxRSS=40872 I/O=0/0 >> >> any idea on how to speed that up? >> >> I have also this rather interesting strace-log for the Go program: >> - https://cern.ch/binet/go-hep/strace-read-go.txt >> >> ie: there is a clear pattern of "epoll_wait/pselect6" on one thread >> followed by a bunch of "pread64" on another thread. >> I suspect this is the runtime I/O layer (?) dispatching data to the >> "worker" thread/goroutine ? >> (I have tried with GOGC=off and it was still there, as well as the same >> timings for my Go binary.) >> >> I have put a ~764Mb data file there: >> - https://cern.ch/binet/go-hep/f64s.root >> >> if anybody wants to have a look. >> >> I initially thought it was a (lack of) bufio.Reader issue (as the file >> format forces you to do a bunch of seeks or readat, using bufio.Reader >> wasn't completely straightforward.) >> but, mmap-ing the whole file in memory didn't help. >> >> here is the top50 from the CPU profile: >> >> (pprof) top50 >> Showing nodes accounting for 12.90s, 99.15% of 13.01s total >> Dropped 4 nodes (cum <= 0.07s) >> flat flat% sum% cum cum% >> 2.83s 21.75% 21.75% 3.21s 24.67% >> go-hep.org/x/hep/rootio.(*LeafD).readBasket >> /home/binet/dev/go/gocode/src/go-hep.org/x/hep/rootio/leaf_gen.go >> 1.35s 10.38% 32.13% 12.99s 99.85% >> go-hep.org/x/hep/rootio.(*Scanner).Scan /home/binet/dev/go/gocode/src/ >> go-hep.org/x/hep/rootio/scanner.go >> 1.26s 9.68% 41.81% 1.26s 9.68% >> go-hep.org/x/hep/rootio.(*tbranch).loadEntry >> /home/binet/dev/go/gocode/src/go-hep.org/x/hep/rootio/basket.go >> 1.17s 8.99% 50.81% 2.01s 15.45% >> go-hep.org/x/hep/rootio.(*tbranch).loadBasket >> /home/binet/dev/go/gocode/src/go-hep.org/x/hep/rootio/branch.go >> 1.15s 8.84% 59.65% 7.15s 54.96% >> go-hep.org/x/hep/rootio.(*tbranch).loadEntry >> /home/binet/dev/go/gocode/src/go-hep.org/x/hep/rootio/branch.go >> 0.82s 6.30% 65.95% 3.06s 23.52% >> go-hep.org/x/hep/rootio.(*tbranch).scan /home/binet/dev/go/gocode/src/ >> go-hep.org/x/hep/rootio/branch.go >> 0.76s 5.84% 71.79% 3.90s 29.98% >> go-hep.org/x/hep/rootio.(*Basket).readLeaf /home/binet/dev/go/gocode/src/ >> go-hep.org/x/hep/rootio/basket.go >> 0.62s 4.77% 76.56% 1.55s 11.91% >> go-hep.org/x/hep/rootio.(*LeafD).scan /home/binet/dev/go/gocode/src/ >> go-hep.org/x/hep/rootio/leaf_gen.go >> 0.56s 4.30% 80.86% 0.56s 4.30% syscall.Syscall6 >> /usr/lib/go/src/syscall/asm_linux_amd64.s >> 0.44s 3.38% 84.24% 0.93s 7.15% reflect.Indirect >> /usr/lib/go/src/reflect/value.go >> 0.38s 2.92% 87.16% 0.38s 2.92% reflect.Value.Elem >> /usr/lib/go/src/reflect/value.go >> 0.34s 2.61% 89.78% 0.34s 2.61% reflect.ValueOf >> /usr/lib/go/src/reflect/value.go >> 0.28s 2.15% 91.93% 0.28s 2.15% >> go-hep.org/x/hep/rootio.(*tbranch).findBasketIndex >> /home/binet/dev/go/gocode/src/go-hep.org/x/hep/rootio/branch.go >> 0.21s 1.61% 93.54% 0.21s 1.61% >> go-hep.org/x/hep/rootio.(*LeafD).Len <autogenerated> >> 0.18s 1.38% 94.93% 0.18s 1.38% >> go-hep.org/x/hep/rootio.(*LeafD).UnmarshalROOT >> /home/binet/dev/go/gocode/src/go-hep.org/x/hep/rootio/rbuffer.go >> 0.17s 1.31% 96.23% 0.17s 1.31% >> go-hep.org/x/hep/rootio.(*tbranch).loadEntry >> /home/binet/dev/go/gocode/src/go-hep.org/x/hep/rootio/rbuffer.go >> 0.11s 0.85% 97.08% 0.11s 0.85% reflect.Value.Elem >> /usr/lib/go/src/reflect/type.go >> 0.09s 0.69% 97.77% 0.09s 0.69% >> go-hep.org/x/hep/rootio.(*Basket).readLeaf /home/binet/dev/go/gocode/src/ >> go-hep.org/x/hep/rootio/rbuffer.go >> 0.09s 0.69% 98.46% 0.09s 0.69% >> go-hep.org/x/hep/rootio.(*LeafD).readBasket >> /usr/lib/go/src/encoding/binary/binary.go >> 0.08s 0.61% 99.08% 0.08s 0.61% >> go-hep.org/x/hep/rootio.(*tleaf).Offset /home/binet/dev/go/gocode/src/ >> go-hep.org/x/hep/rootio/leaf.go >> 0.01s 0.077% 99.15% 13.01s 100% main.main >> /tmp/acat/read-data.go >> 0 0% 99.15% 0.56s 4.30% >> go-hep.org/x/hep/rootio.(*File).ReadAt /home/binet/dev/go/gocode/src/ >> go-hep.org/x/hep/rootio/file.go >> 0 0% 99.15% 0.11s 0.85% >> go-hep.org/x/hep/rootio.(*Key).load /home/binet/dev/go/gocode/src/ >> go-hep.org/x/hep/rootio/key.go >> 0 0% 99.15% 0.56s 4.30% internal/poll.(*FD).Pread >> /usr/lib/go/src/internal/poll/fd_unix.go >> 0 0% 99.15% 0.11s 0.85% io.(*SectionReader).Read >> /usr/lib/go/src/io/io.go >> 0 0% 99.15% 0.11s 0.85% io.ReadAtLeast >> /usr/lib/go/src/io/io.go >> 0 0% 99.15% 0.11s 0.85% io.ReadFull >> /usr/lib/go/src/io/io.go >> 0 0% 99.15% 0.56s 4.30% os.(*File).ReadAt >> /usr/lib/go/src/os/file.go >> 0 0% 99.15% 0.56s 4.30% os.(*File).pread >> /usr/lib/go/src/os/file_unix.go >> 0 0% 99.15% 13.01s 100% runtime.main >> /usr/lib/go/src/runtime/proc.go >> 0 0% 99.15% 0.56s 4.30% syscall.Pread >> /usr/lib/go/src/syscall/zsyscall_linux_amd64.go >> >> >> anything obvious I missed ? >> >> cheers, >> -s >> > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. 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