<div dir="ltr">The garbage collection handbook has many references to statistics of pointers in the heap. In particular, Gen GC chapter - Pointer Direction (p125) says:<div><br></div><div>"[...] Many pointer writes are initialising stores to newly created objects - Zorn[1990] estimated that 90% to 95% of lisp pointer stores were initialising (and that of the remaining non-initialising stores two-thirds were to objects in the young generation) [...]"</div><div><br></div><div>so (if this also applies to Smalltalk) ~98% makes sense (90%+6,666%)</div><div><br></div><div>I guess the cited paper is this one:</div><div><br></div><div><a href="http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.52.8857" target="_blank">http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.52.8857</a></div><div><br></div><div>cheers,</div><div>pocho<br><div><br></div><div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Jul 25, 2016 at 11:35 AM, Clément Bera <span dir="ltr"><<a href="mailto:bera.clement@gmail.com" target="_blank">bera.clement@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> <br><div dir="ltr">Hi,<div><br></div><div>We changed recently with Eliot some part of the JIT to generate more efficient code for young objects mutation, speeding up a bit binary trees, especially when read-only objects are available. We did it only for quick inst var stores (popIntoInstanceVariable for inst var index between 0 and 7 on non context objects) as it was easier to narrow the optimization to this case and it is the most common case.</div><div><br></div><div>When starting-up a REPL image, there are 7221 mutations of objects through the quick inst var store bytecode, and 7082 are done on young objects. Hence, 98% of mutations for these bytecodes are done on young objects. </div><div><br></div><div>Has anyone numbers from papers / large application on how many stores are done on young objects compared to stores done on old objects ? Does 98% sound reasonable ?</div><div><br></div><div>Regards,</div><div><br></div><div>Clement</div></div>
<br></blockquote></div><br><br clear="all"><div><br></div>-- <br><div data-smartmail="gmail_signature"><div dir="ltr">Javier Pimás<br>Ciudad de Buenos Aires</div></div>
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