[ruby-core:91159] Re: Testing MJIT on RHEL 7.5

Hi,

> time /usr/local/ruby-edge/bin/ruby --disable-gems --jit -e "5000000.times { 3 * 123 }"
> real    0m0.229s

229ms is too short to measure JIT-ed code's performance. Because of this:

$ time ./ruby --disable-gems -e ""
./ruby --disable-gems -e ""  0.00s user 0.00s system 95% cpu 0.005 total
$ time ./ruby --disable-gems --jit -e ""
./ruby --disable-gems --jit -e ""  0.12s user 0.02s system 100% cpu 0.135 total

large amount of time you measure would be just time consumed for
stopping JIT thread.
This behavior is limitation of JIT-ing by invoking C compiler, and
this is something intentional for now.

Due to that, what we can do for now is just like (this is ruby 2.6.0
x86_64-linux):

$ time ./ruby --disable-gems -e "500000000.times { 3 * 123 }"
./ruby --disable-gems -e "500000000.times { 3 * 123 }"  13.24s user
0.00s system 99% cpu 13.242 total
$ time ./ruby --disable-gems --jit -e "500000000.times { 3 * 123 }"
./ruby --disable-gems --jit -e "500000000.times { 3 * 123 }"  10.13s
user 0.02s system 101% cpu 9.989 total

Best,
k0kubun

2019年1月18日(金) 10:34 Phil Edelbrock <[e-mail]>:
>
>
> Hello, I'm new to this list.  I hope this is the right place to ask questions about the new experimental JIT implementation (which looks incredibly cool).
>
> First, I've got both 2.6.0 installed and the latest from github (which I call 'edge') on RHEL 7.5:
>
> [pedelbro@966629-app3 ~]$ /usr/local/ruby-2.6.0/bin/ruby -v
> ruby 2.6.0p0 (2018-12-25 revision 66547) [x86_64-linux]
> [pedelbro@966629-app3 ~]$ /usr/local/ruby-edge/bin/ruby -v
> ruby 2.7.0dev (2019-01-16 trunk 66836) [x86_64-linux]
>
> gcc:
>
> Thread model: posix
> gcc version 4.8.5 20150623 (Red Hat 4.8.5-28) (GCC)
>
> My /tmp is mounted (by default) as NOEXEC, so I created a regular directory in my home directory to get around the permissions error/warning:
>
> MJIT warning: failure in loading code from '/tmp/_ruby_mjit_p108878u0.so': /tmp/_ruby_mjit_p108878u0.so: failed to map segment from shared object: Operation not permitted
>
> So, now things seem better:
>
> MJIT: CC defaults to /usr/bin/gcc
> MJIT: tmp_dir is /home/pedelbro/my_tmp
> Creating precompiled header
> Starting process: /usr/bin/gcc /usr/bin/gcc -std=gnu99 -w -Wfatal-errors -fPIC -shared -w -pipe -O3 -nodefaultlibs -nostdlib -o /home/pedelbro/my_tmp/_ruby_mjit_hp116911u0.h.gch /usr/local/ruby-edge/include/ruby-2.7.0/x86_64-linux/rb_mjit_min_header-2.7.0.h
> start compilation: block in <main>@-e:1 -> /home/pedelbro/my_tmp/_ruby_mjit_p116911u0.c
> Starting process: /usr/bin/gcc /usr/bin/gcc -std=gnu99 -w -Wfatal-errors -fPIC -shared -w -pipe -O3 -o /home/pedelbro/my_tmp/_ruby_mjit_p116911u0.o /home/pedelbro/my_tmp/_ruby_mjit_p116911u0.c -c -lgcc -Wl,--compress-debug-sections=zlib -nostartfiles -nodefaultlibs -nostdlib
> Starting process: /usr/bin/gcc /usr/bin/gcc -std=gnu99 -shared -Wfatal-errors -fPIC -shared -w -pipe -O3 -o /home/pedelbro/my_tmp/_ruby_mjit_p116911u0.so /home/pedelbro/my_tmp/_ruby_mjit_p116911u0.o -lgcc -Wl,--compress-debug-sections=zlib -nostartfiles -nodefaultlibs -nostdlib
> JIT success (37.9ms): block in <main>@-e:1 -> /home/pedelbro/my_tmp/_ruby_mjit_p116911u0.c
>
> When testing, though, I only see slowdowns when turning on JIT?
>
> This is a simple (and maybe a bad) example:
>
> [pedelbro@966629-app3 models]$ time /usr/local/ruby-edge/bin/ruby --disable-gems --jit -e "5000000.times { 3 * 123 }"
>
> real    0m0.229s
> user    0m0.383s
> sys     0m0.049s
> [pedelbro@966629-app3 models]$ time /usr/local/ruby-edge/bin/ruby --disable-gems -e "5000000.times { 3 * 123 }"
>
> real    0m0.208s
> user    0m0.203s
> sys     0m0.004s
>
> Thanks!  Let me know if this is the wrong list to discuss this.  I hope to be another datapoint for testing, if it helps. :')
>
>
> Phil
>
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