{"id":3355,"date":"2018-03-21T00:02:06","date_gmt":"2018-03-21T00:02:06","guid":{"rendered":"https:\/\/blogs.msdn.microsoft.com\/pix\/?page_id=3355"},"modified":"2018-03-21T00:02:06","modified_gmt":"2018-03-21T00:02:06","slug":"collecting-cpu-samples-in-timing-captures","status":"publish","type":"page","link":"https:\/\/devblogs.microsoft.com\/pix\/collecting-cpu-samples-in-timing-captures\/","title":{"rendered":"Collecting CPU Samples in Timing Captures"},"content":{"rendered":"

PIX includes a CPU sampling profiler that can optionally be run when taking a timing capture. Viewing CPU samples is useful for determining what code is running on a thread or core for portions of your title that either have sparse or no instrumentation with PIX events.<\/p>\n

For example, in the following timeline you can see the main thread of this title (AP1) has only one PIX event that spans approximately 32ms of time.<\/p>\n

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Collecting CPU samples allows you to get a sense for what functions in your title are executing during that time range without having to add further instrumentation, rebuild and redeploy.<\/span><\/p>\n

Before collecting samples, PIX must be configured to find your title\u2019s PDBs.\u00a0 <\/span>Symbol information in the PDBs is used to display function names for the CPU samples PIX collects.\u00a0 <\/span>See Configuring PIX to access CPU PDBs<\/a> for more information.<\/span><\/p>\n

To collect CPU samples, select the Capture CPU Samples<\/strong> checkbox on the Timing Capture options pane.<\/span><\/p>\n

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Collecting samples causes PIX to add one additional lane to the Timeline for each thread or core.\u00a0 <\/span>The samples are displayed on this new \u201cFunctions\u201d lane.\u00a0 <\/span>Samples are drawn as small rectangles.\u00a0 <\/span>The following picture shows several samples that were collected during the time a single long PIX event was executing:<\/span><\/p>\n

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The current sampling rate is 1ms.\u00a0 <\/span>Future versions of PIX will allow you to tune this sampling rate for finer control over level of detail and overhead.<\/span><\/p>\n

Selecting a sample causes the Event Details view to be populated with the callstack for the sample.<\/span><\/p>\n

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The column of checkboxes in the Tracked<\/strong> column allows you to add and remove the functions in the callstack from the list of functions that will be tracked and displayed on the timeline in subsequent captures.\u00a0 <\/span>See Tracked Functions in Timing Captures<\/a> for more details.\u00a0<\/span><\/p>\n

The Stack Analysis view can also be used to look at samples.\u00a0 <\/span>This view contains a rollup of all samples that were collected during the capture.\u00a0 <\/span>As PIX is collecting samples, it aggregates identical callstacks so you can see which functions and specific callstacks appeared most frequently in the samples.\u00a0 <\/span>Samples are aggregated for each thread in the capture.<\/span><\/p>\n

Columns that show the inclusive and exclusive percentages and the inclusive and exclusive counts for each function and callstack are provided.\u00a0 <\/span>The Track and Untrack buttons on the view can be used to manipulate the list of functions that will be tracked in subsequent timing captures.<\/span><\/p>\n

\"\"<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

PIX includes a CPU sampling profiler that can optionally be run when taking a timing capture. Viewing CPU samples is useful for determining what code is running on a thread or core for portions of your title that either have sparse or no instrumentation with PIX events. For example, in the following timeline you can […]<\/p>\n","protected":false},"author":1915,"featured_media":4769,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"footnotes":""},"class_list":["post-3355","page","type-page","status-publish","has-post-thumbnail","hentry"],"acf":[],"_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/pix\/wp-json\/wp\/v2\/pages\/3355","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/pix\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/pix\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/pix\/wp-json\/wp\/v2\/users\/1915"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/pix\/wp-json\/wp\/v2\/comments?post=3355"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/pix\/wp-json\/wp\/v2\/pages\/3355\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/pix\/wp-json\/wp\/v2\/media\/4769"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/pix\/wp-json\/wp\/v2\/media?parent=3355"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}