<div dir="ltr">First post from the internet about <span style="font-family:monospace">xen_hypercall_event_channel_op:</span> <a href="https://www.scylladb.com/2018/06/21/impact-virtualization-database/">https://www.scylladb.com/2018/06/21/impact-virtualization-database/</a><div><br></div><div>TL;DR: metal server better than virtual</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Jul 6, 2020 at 5:26 PM Fernando Benavides <<a href="mailto:elbrujohalcon@gmail.com">elbrujohalcon@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div class="gmail_default" style="font-family:"trebuchet ms",sans-serif">I'll add another data point…</div><div class="gmail_default" style="font-family:"trebuchet ms",sans-serif">As Lukas suggested, I used <i>perf</i> on the running systems and this is what I've got…</div><div class="gmail_default" style="font-family:"trebuchet ms",sans-serif"><br></div><div class="gmail_default" style="font-family:"trebuchet ms",sans-serif">For OTP22:</div><div class="gmail_default"><font face="monospace"> 2.33% 8_scheduler beam.smp [.] process_main<br><i> …the rest of the schedulers running process_main…<br></i> 1.57% 6_scheduler beam.smp [.] process_main<br> 0.34% 6_scheduler [kernel.kallsyms] [k] xen_hypercall_event_channel_op<br> 0.32% 7_scheduler [kernel.kallsyms] [k] xen_hypercall_event_channel_op<br> 0.25% 14_scheduler beam.smp [.] copy_struct_x<br> 0.25% 2_scheduler beam.smp [.] copy_struct_x<br> 0.25% 9_scheduler [kernel.kallsyms] [k] xen_hypercall_event_channel_op<br> 0.23% 11_scheduler [kernel.kallsyms] [k] xen_hypercall_event_channel_op<br> 0.22% 11_scheduler beam.smp [.] copy_shallow_x<br> 0.22% 9_scheduler <a href="http://libc-2.17.so" target="_blank">libc-2.17.so</a> [.] __memcpy_ssse3_back<br> 0.20% 13_scheduler [kernel.kallsyms] [k] __lock_text_start<br> 0.20% 3_scheduler [kernel.kallsyms] [k] xen_hypercall_event_channel_op<br> 0.19% 10_scheduler beam.smp [.] erts_cmp_compound<br></font></div><div class="gmail_default" style="font-family:"trebuchet ms",sans-serif"><br></div><div class="gmail_default" style="font-family:"trebuchet ms",sans-serif">For OTP21:</div><div class="gmail_default"><font face="monospace"> 2.45% 4_scheduler beam.smp [.] process_main<br><i> …the rest of the schedulers running process_main…<br></i> 1.91% 5_scheduler beam.smp [.] process_main<br> 0.45% 15_scheduler [kernel.kallsyms] [k] __lock_text_start<br> 0.27% 10_scheduler [kernel.kallsyms] [k] __lock_text_start<br> 0.27% 3_scheduler [kernel.kallsyms] [k] __lock_text_start<br> 0.27% 7_scheduler [kernel.kallsyms] [k] __lock_text_start<br> 0.25% 1_scheduler beam.smp [.] copy_struct_x<br> 0.25% 2_scheduler [kernel.kallsyms] [k] __lock_text_start<br> 0.23% 2_scheduler beam.smp [.] copy_struct_x<br> 0.23% 7_scheduler beam.smp [.] copy_struct_x<br> 0.20% 4_scheduler beam.smp [.] copy_struct_x<br> 0.20% 6_scheduler [kernel.kallsyms] [k] __lock_text_start<br> 0.18% 14_scheduler beam.smp [.] copy_struct_x</font><br></div><div class="gmail_default"><font face="monospace"><br></font></div><div class="gmail_default"><font face="trebuchet ms, sans-serif">I'm not sure what any of those functions are, or why </font><font face="monospace">xen_hypercall_event_channel_op</font><font face="trebuchet ms, sans-serif"> is so much popular in OTP22, tho… 🤔</font></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Jul 6, 2020 at 3:42 PM Max Lapshin <<a href="mailto:max.lapshin@gmail.com" target="_blank">max.lapshin@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">In a nutshell there is a non-reproducible fluctuation of measurement: one subsystem takes 10% instead 8%, another 21% instead 23%.<div><br></div><div>Totally there seems to be no change.</div><div><br></div><div>It is extremely hard to make reliable measurement that helps to find 8% to 10% change.</div></div>
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