<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">Hello,<div><br></div><div>Here I’ve compiled a small project to benchmark the issue:</div><div><br></div><div>git clone <a href="https://github.com/fogfish/fjsx">https://github.com/fogfish/fjsx</a></div><div>make</div><div>make run</div><div>(<a href="mailto:fjsx@127.0.0.1">fjsx@127.0.0.1</a>)1> fjsx:run().</div><div><br></div><div>My results are following:</div><div>R15B03: min 2.9K, avg 3.1K, max 3.3K</div><div>R16B03: min 2.7K, avg 2.8K, max 3.0K </div><div><br></div><div>(In production I do much more staff, it shown even worse degradation)</div><div><br></div><div>I run the test on virtual machine, cent os 6 x86_64 with 4 virtual CPU (underlying HW MacBook Pro i5, 2.5GHz).</div><div>Virtual CPU</div><div>vendor_id<span class="Apple-tab-span" style="white-space:pre"> </span>: GenuineIntel<br>cpu family<span class="Apple-tab-span" style="white-space:pre"> </span>: 6<br>model<span class="Apple-tab-span" style="white-space:pre"> </span>: 58<br>model name<span class="Apple-tab-span" style="white-space:pre"> </span>: Intel(R) Core(TM) i5-3210M CPU @ 2.50GHz<br>stepping<span class="Apple-tab-span" style="white-space:pre"> </span>: 9<br>cpu MHz<span class="Apple-tab-span" style="white-space:pre"> </span>: 2535.252<br>cache size<span class="Apple-tab-span" style="white-space:pre"> </span>: 6144 KB<br>physical id<span class="Apple-tab-span" style="white-space:pre"> </span>: 0<br>siblings<span class="Apple-tab-span" style="white-space:pre"> </span>: 4<br>core id<span class="Apple-tab-span" style="white-space:pre"> </span>: 3<br>cpu cores<span class="Apple-tab-span" style="white-space:pre"> </span>: 4<br>apicid<span class="Apple-tab-span" style="white-space:pre"> </span>: 3<br>initial apicid<span class="Apple-tab-span" style="white-space:pre"> </span>: 3<br>fpu<span class="Apple-tab-span" style="white-space:pre"> </span>: yes<br>fpu_exception<span class="Apple-tab-span" style="white-space:pre"> </span>: yes<br>cpuid level<span class="Apple-tab-span" style="white-space:pre"> </span>: 5<br>wp<span class="Apple-tab-span" style="white-space:pre"> </span>: yes<br>flags<span class="Apple-tab-span" style="white-space:pre"> </span>: fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx rdtscp lm constant_tsc rep_good pni ssse3 lahf_lm<br>bogomips<span class="Apple-tab-span" style="white-space:pre"> </span>: 5070.50<br>clflush size<span class="Apple-tab-span" style="white-space:pre"> </span>: 64<br>cache_alignment<span class="Apple-tab-span" style="white-space:pre"> </span>: 64<br>address sizes<span class="Apple-tab-span" style="white-space:pre"> </span>: 36 bits physical, 48 bits virtual<br>power management:<br><br>otp configuration is identical for R15 and R16</div><div><br></div><div>R15B03: config.log</div><div> $ ./configure --prefix=/usr/local/otp_R15B03 --enable-threads --enable-smp-support --enable-kernel-poll --enable-hipe --disable-dynamic-ssl-lib --with-ssl=/usr/local/ssl --enable-native-libs</div><div><br></div><div>R16B03: config.log</div><div> $ ./configure --prefix=/usr/local/otp_R16B03 --enable-threads --enable-smp-support --enable-kernel-poll --enable-hipe --disable-dynamic-ssl-lib --with-ssl=/usr/local/ssl --enable-native-libs</div><div><br></div><div>I have not run the test on real HW:</div><div> - my mac’s OTP configurations are different R16B03 enables --enable-darwin-64bit therefor it outperforms R15</div><div> - my production is virtual machines </div><div><br></div><div>I’ve been using eep to profile the issue. You can go same to compare R16 and R15 differences.</div><div><br></div><div>Best Regards, </div><div>Dmitry</div><div><br></div><div><div><div>On 28 Jan 2014, at 11:54, Lukas Larsson <<a href="mailto:lukas@erlang.org">lukas@erlang.org</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div dir="ltr">Hello,<div><br></div><div>The code for formatting float when doing it through io_lib:format it written in pure Erlang. The reason that io_lib:format is implemented in Erlang is because it allows much greater cross platform formatting capabilities, alas at the cost of performance. </div>
<div><br></div><div>Why you see a performance drop in between R15B03 to R16B03 I don't know, if you could create a minimal reproducible benchmark that shows the difference that would be great.</div><div><br></div><div>
If you want to have a speedy conversion of something you know is a float to a textual format you should use float_to_list/binary as that is meant to be a fast conversion, but with less flexibility.</div><div><br></div><div>
Lukas</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, Jan 28, 2014 at 10:05 AM, Max Lapshin <span dir="ltr"><<a href="mailto:max.lapshin@gmail.com" target="_blank">max.lapshin@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_extra">btw, why io_lib:format is so slow? simple changing it to nif with fprintf reduces cpu a lot.</div>
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