<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Oct 13, 2016, at 5:22 PM, Teresa Johnson <<a href="mailto:tejohnson@google.com" class="">tejohnson@google.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><br class="Apple-interchange-newline"><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><div class="gmail_quote" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;">On Thu, Oct 13, 2016 at 5:14 PM, Mehdi Amini<span class="Apple-converted-space"> </span><span dir="ltr" class=""><<a href="mailto:mehdi.amini@apple.com" target="_blank" class="">mehdi.amini@apple.com</a>></span><span class="Apple-converted-space"> </span>wrote:<br class=""><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;"><span class=""><br class="">> On Oct 13, 2016, at 5:07 PM, Teresa Johnson <<a href="mailto:tejohnson@google.com" target="_blank" class="">tejohnson@google.com</a>> wrote:<br class="">><br class="">> tejohnson added inline comments.<br class="">><br class="">><br class="">> ================<br class="">> Comment at: include/llvm/Support/Threading<wbr class="">.h:121<br class="">> + /// host system, otherwise falls back to thread::hardware_concurrency()<wbr class="">.<br class="">> + unsigned hardware_physical_concurrency(<wbr class="">);<br class="">> }<br class="">> ----------------<br class="">> mehdi_amini wrote:<br class="">>> I think we may want to name it `hardware_coarse_concurrency`. Because:<br class="">>><br class="">>> - This looks like expressing better what we're looking after.<br class="">>> - Hyperthreading is in some sense "physical concurrency", but sharing some resources.<br class="">>> - Other platforms may have something in between.<br class="">>><br class="">> I thought about that name after you mentioned it on the prior review thread. But I felt that saying "physical concurrency" is a better expression for what it is actually trying to give you. I think of the hyperthreading concurrency as "logical concurrency", vs physical concurrency due to physical cores.<br class=""><br class=""></span>Hyperthreading is sharing some physical resources on the core, but have some other physical resources duplicated/dedicated, which is why I feel it is murky. But “good enough” as well...<br class="">Also, I don’t know enough the PowerPC or Sparc equivalent of hyper-threading to know how much they share/duplicate and what we would pick on these for instance.<br class=""></blockquote><div class=""><br class=""></div><div class="">Right it is a bit murky. One reason I didn't like "coarse" is that coarse-grained parallelism relates to how closely the tasks communicate/synchronize</div></div></div></blockquote><div><br class=""></div><div>Fair.</div><div>In my mind “coarse” relates to the “size” of the task. But a few light and long-lived task could fit a “coarse” level of granularity.</div><div><br class=""></div><div>I don’t have anything better to qualify these tasks (“heavy” is kind of what I’m looking for, but I can’t translate this into an API name…).</div><div><br class=""></div><div><br class=""></div><br class=""><blockquote type="cite" class=""><div class=""><div class="gmail_quote" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><div class="">, and I while ThinLTO backend tasks would qualify, I don't think that's why they don't scale well beyond the # physical cores (but rather the memory intensiveness as you pointed out in the other thread). I'll go with this for now.</div><div class=""><br class=""></div><div class=""><br class=""></div><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;"><br class="">—<br class=""><span class="m_810626850731252243HOEnZb"><font color="#888888" class="">Mehdi<br class=""><br class=""><br class=""><br class=""></font></span></blockquote></div><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><br clear="all" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><br class=""></div><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">--<span class="Apple-converted-space"> </span></span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><div class="m_810626850731252243gmail_signature" data-smartmail="gmail_signature" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><span style="font-family: Times; font-size: inherit;" class=""><table cellspacing="0" cellpadding="0" class=""><tbody class=""><tr style="color: rgb(85, 85, 85); font-family: sans-serif; font-size: small;" class=""><td nowrap="" style="border-top-style: solid; border-top-color: rgb(213, 15, 37); border-top-width: 2px;" class="">Teresa Johnson |</td><td nowrap="" style="border-top-style: solid; border-top-color: rgb(51, 105, 232); border-top-width: 2px;" class=""> Software Engineer |</td><td nowrap="" style="border-top-style: solid; border-top-color: rgb(0, 153, 57); border-top-width: 2px;" class=""> <a href="mailto:tejohnson@google.com" target="_blank" class="">tejohnson@google.com</a> |</td><td nowrap="" style="border-top-style: solid; border-top-color: rgb(238, 178, 17); border-top-width: 2px;" class=""> <a href="tel:408-460-2413" value="+14084602413" target="_blank" class="">408-460-2413</a></td></tr></tbody></table></span></div></div></blockquote></div><br class=""></body></html>