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--></style></head><body lang=ZH-CN link=blue vlink="#954F72" style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal><span lang=EN-US>Hi,</span></p><p class=MsoNormal><span lang=EN-US>Recently, my company is gradually upgrading JDK from 8 to 17. And I did some tests. </span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Under the same qps, I found the follow Phenomenon</span></p><p class=MsoListParagraph style='margin-left:18.0pt;text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span lang=EN-US><span style='mso-list:Ignore'>1.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span lang=EN-US>different heap size, Memory Allocation Rate(in zgc gc statistics) are similar</span><span lang=EN-US style='font-size:12.0pt'><o:p></o:p></span></p><p class=MsoListParagraph style='margin-left:18.0pt;text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span lang=EN-US><span style='mso-list:Ignore'>2.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span lang=EN-US>the smaller the heap size(bigger gc pressure)</span>，<span lang=EN-US>the Allocation rate which calculated by com.sun.management.GcInfo(usageBeforeGc- usageAfterGc) is more bigger than Memory Allocation Rate(in zgc gc statistics)</span><span lang=EN-US style='font-size:12.0pt'><o:p></o:p></span></p><p class=MsoListParagraph style='margin-left:18.0pt;text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span lang=EN-US><span style='mso-list:Ignore'>3.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span lang=EN-US>the bigger the heap size</span>，<span lang=EN-US>the Allocation rate which calculated by com.sun.management.GcInfo is more close to Memory Allocation Rate(in zgc gc statistics)</span><span lang=EN-US style='font-size:12.0pt'><o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:12.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:12.0pt'>I wonder what mechanism causes this. Why the more bigger gc pressure, the</span><span lang=EN-US> Allocation rate which calculated by com.sun.management.GcInfo is more bigger</span><span lang=EN-US style='font-size:12.0pt'><o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:12.0pt;font-family:SimSun'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:12.0pt;font-family:SimSun'>Thanks,<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:12.0pt;font-family:SimSun'>Wang kang <o:p></o:p></span></p></div></body></html>