{"id":453,"date":"2011-10-13T22:48:13","date_gmt":"2011-10-13T21:48:13","guid":{"rendered":"http:\/\/www.p2vpro.com\/?p=453"},"modified":"2011-10-13T22:52:12","modified_gmt":"2011-10-13T21:52:12","slug":"the-vsphere-limit-effect","status":"publish","type":"post","link":"https:\/\/www.p2vpro.com\/?p=453","title":{"rendered":"The vSphere limit effect"},"content":{"rendered":"

\"VMware<\/a>

VMware Limit Effect on Linux top<\/p><\/div>I believe the effects of limiting a guests CPU in vsphere are well understood but I for one don’t like the way VMware implement this. I have just verified the behaviour on ESXi 5.0.0 is the same as 4.1 (which is only to be expected).<\/p>\n

Guests get confused, is the bottom line. At least Linux does, which is particularly noticable with “top”. In the screenshot above of a Centos guest, I have limited the CPU to 1000Mhz using virtualcenter. To me, it would be logical that the guest O\/S would be presented with a 1000Mhz CPU but this is not the case. The output of \/proc\/cpuinfo means that Linux thinks it is running on a 3.47Ghz i5. Is it really hard to do, or something?<\/p>\n

The upshot is that when the guest is maxed out, as in the screenshot, top shows 100% us time (correct) but only 29% of the CPU. Which is correct if you consider the pCPU but not, if like me you don’t think a guest should have any knowledge of the real hardware. I think Centos should see a 1000Mhz vCPU and top will correctly display 100% CPU Time.<\/p>\n

Must check this on other hypervisors (Xen and KVM) sometime.<\/p>\n

P.S.
\nSaddened to hear of the death of Dennis Ritchie today. Someone who I can identify as having a large impact on my life, though I never knew or met him. Such is the world we live in. Eventually we will all exit(0).<\/p>\n","protected":false},"excerpt":{"rendered":"

I believe the effects of limiting a guests CPU in vsphere are well understood but I for one don’t like the way VMware implement this. I have just verified the behaviour on ESXi 5.0.0 is the same as 4.1 (which … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[30,24],"class_list":["post-453","post","type-post","status-publish","format-standard","hentry","category-virtualisation","tag-centos","tag-esxi"],"_links":{"self":[{"href":"https:\/\/www.p2vpro.com\/index.php?rest_route=\/wp\/v2\/posts\/453","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.p2vpro.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.p2vpro.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.p2vpro.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.p2vpro.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=453"}],"version-history":[{"count":6,"href":"https:\/\/www.p2vpro.com\/index.php?rest_route=\/wp\/v2\/posts\/453\/revisions"}],"predecessor-version":[{"id":459,"href":"https:\/\/www.p2vpro.com\/index.php?rest_route=\/wp\/v2\/posts\/453\/revisions\/459"}],"wp:attachment":[{"href":"https:\/\/www.p2vpro.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=453"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.p2vpro.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=453"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.p2vpro.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=453"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}