<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Apr 24, 2017, at 8:52 PM, Pavol Vaskovic <<a href="mailto:pali@pali.sk" class="">pali@pali.sk</a>> wrote:</div><div class=""><div class=""><br class=""><blockquote type="cite" class="">On 25 Apr 2017, at 01:28, Greg Parker <<a href="mailto:gparker@apple.com" class="">gparker@apple.com</a>> wrote:<br class=""><br class="">The value of MAX_RSS depends on OS behavior. Other activity on the same machine may change MAX_RSS of the benchmark.<br class=""></blockquote><br class="">Can you please describe the mechanism of how “other activity on the same machine may change MAX_RSS of the benchmark”.?<br class=""></div></div></blockquote><div><br class=""></div><div>Not all memory used by the benchmark counts against its RSS. For example, paged-out and VM-compressed memory are both excluded. If there are other processes contending for memory while the benchmark runs then the benchmark's RSS will be artificially reduced.</div><div><br class=""></div><div>Did you see any time difference between the 3MB and the 10MB runs? </div><div><br class=""></div><br class=""><blockquote type="cite" class=""><div class=""><div class=""><blockquote type="cite" class="">The changes you saw might not be "real”.<br class=""></blockquote></div></div></blockquote><blockquote type="cite" class=""><br class=""></blockquote><blockquote type="cite" class=""><div class=""><div class="">How was that not real? I have logs that prove that. See the attachment in original post.<br class=""></div></div></blockquote><div><br class=""></div><div>The possibility is that the benchmark's RSS did in fact change, but the benchmark's "real" memory usage did not.</div><div><br class=""></div><br class=""><blockquote type="cite" class=""><div class=""><div class=""><blockquote type="cite" class="">If you re-run the 2017-04-15 builds today, do you still see 3 MB instead of 10 MB?</blockquote><br class="">Nope. If I saw it now, I wouldn’t be searching for that, but congratulating the brave committer that gave us this improvement. </div></div></blockquote><br class=""></div><div>That tends to suggest a difference in the test environment rather than a change in Swift. If some Swift changes were responsible for the RSS decrease and subsequent increase then re-running the benchmark with that version of Swift ought to exhibit the same RSS behavior.</div><div><br class=""></div><div>Measuring memory usage is good. RSS is a difficult value to use for such measurements.</div><div><br class=""></div><div><br class=""></div><div>-- </div><div>Greg Parker <a href="mailto:gparker@apple.com" class="">gparker@apple.com</a> Runtime Wrangler</div><div><br class=""></div><div><br class=""></div></body></html>