<html><head></head><body bgcolor="#FFFFFF"><div>Capacity based scheduling currently adds up all instance usage in host_manager.py</div><div><br></div><div>There's another review marked as WIP that will be ready when retries go in that cleans that and the capacity tracking up. Look for it from Brian Elliott.<br><br>On Jul 13, 2012, at 6:38 AM, "Day, Phil" <<a href="mailto:philip.day@hp.com">philip.day@hp.com</a>> wrote:<br><br></div><div></div><blockquote type="cite"><div><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"><meta name="Generator" content="Microsoft Word 14 (filtered medium)"><style><!--
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</o:shapelayout></xml><![endif]--><div class="WordSection1"><p class="MsoNormal">Hi Folks,<o:p></o:p></p><p class="MsoNormal"><o:p> </o:p></p><p class="MsoNormal">I was reviewing a code change to add generic retries for build failures ( <a href="https://review.openstack.org/#/c/9540/2">https://review.openstack.org/#/c/9540/2</a> ), and wanted to be sure that it wouldn’t invalidate the capacity accounting used by the scheduler.<o:p></o:p></p><p class="MsoNormal"><o:p> </o:p></p><p class="MsoPlainText">However I've been sitting here for a while working through the Folsom scheduler code trying to understand how the capacity based scheduling now works, and I’m sure I’m missing something obvious but I just can’t work out where the free_ram_mb value in the compute_node table gets updated.<o:p></o:p></p><p class="MsoPlainText"><o:p> </o:p></p><p class="MsoPlainText">I can see the database api method to update the values, compute_node_utilization_update(), it doesn’t look as if anything in the code ever calls that ?<o:p></o:p></p><p class="MsoPlainText"><o:p> </o:p></p><p class="MsoPlainText">From when I last looked at this / various discussions here and at the design summits I thought the approach was that:<o:p></o:p></p><p class="MsoPlainText"> <o:p></o:p></p><p class="MsoPlainText" style="margin-left:54.0pt;text-indent:-18.0pt;mso-list:l0 level1 lfo1"><!--[if !supportLists]--><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman""> </span></span><!--[endif]-->The scheduler would make a call (rather than a cast) to the compute manger, which would then do some verification work, update the DB table whilst in the context of that call, and then start a thread to complete the spawn. The need to go all the way to the compute node as a call was to avoid race conditions from multiple schedulers. (the change I’m looking at is part of a blueprint to avoid such a race, so maybe I imagined the change from cast to call ?)<o:p></o:p></p><p class="MsoPlainText" style="margin-left:54.0pt"><o:p> </o:p></p><p class="MsoPlainText" style="margin-left:54.0pt;text-indent:-18.0pt;mso-list:l0 level1 lfo1"><!--[if !supportLists]--><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman""> </span></span><!--[endif]-->On a delete, the capacity_notifer (which had to be configured into the list_notifier) would detect the delete message, and decrement the database values.<o:p></o:p></p><p class="MsoPlainText"><o:p> </o:p></p><p class="MsoPlainText">But now I look through the code it looks as if the scheduler is still doing a cast (scheduler/driver), and although I can see the database api call to update the values, compute_node_utilization_update(), it doesn’t look as if anything in the code ever calls that ?<o:p></o:p></p><p class="MsoPlainText"><o:p> </o:p></p><p class="MsoPlainText">The ram_filter scheduler seems to use the free_ram_mb value, and that value seems to come from the host_manager in the scheduler which is read from the Database, but I can't for the life of me work out where these values are updated in the Database.<o:p></o:p></p><p class="MsoPlainText"><o:p> </o:p></p><p class="MsoPlainText">The capacity_notifier, which used to decrement values on a VM deletion only (according to the comments the increment was done in the scheduler) seems to have now disappeared altogether in the move of the notifier to openstack/common ?<o:p></o:p></p><p class="MsoPlainText" style="margin-left:36.0pt"><o:p> </o:p></p><p class="MsoPlainText">So I’m sure I’m missing some other even more cunning plan on how to keep the values current, but I can’t for the life of me work out what it is – can someone fill me in please ?<o:p></o:p></p><p class="MsoPlainText"><o:p> </o:p></p><p class="MsoPlainText">Thanks,<o:p></o:p></p><p class="MsoPlainText">Phil<o:p></o:p></p><p class="MsoNormal"><o:p> </o:p></p></div></div></blockquote><blockquote type="cite"><div><span>_______________________________________________</span><br><span>Mailing list: <a href="https://launchpad.net/~openstack">https://launchpad.net/~openstack</a></span><br><span>Post to : <a href="mailto:openstack@lists.launchpad.net">openstack@lists.launchpad.net</a></span><br><span>Unsubscribe : <a href="https://launchpad.net/~openstack">https://launchpad.net/~openstack</a></span><br><span>More help : <a href="https://help.launchpad.net/ListHelp">https://help.launchpad.net/ListHelp</a></span><br></div></blockquote></body></html>