Messages in this thread | | | From | Suren Baghdasaryan <> | Date | Thu, 26 Jul 2018 15:11:39 -0700 | Subject | Re: [PATCH v2 10/12] sched/core: uclamp: use TG's clamps to restrict Task's clamps |
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<div dir="ltr">Sorry for the delay. Overlooked this comment...<br><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Jul 24, 2018 at 8:49 AM, Patrick Bellasi <span dir="ltr"><<a href="mailto:patrick.bellasi@arm.com" target="_blank">patrick.bellasi@arm.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><span class="gmail-">On 24-Jul 08:28, Suren Baghdasaryan wrote:<br> > Hi Patrick. Thanks for the explanation and links. No more questions<br> > from me on this one :)<br> <br> </span>No problems at all!<br> <br> The important question is instead: does it makes sense for you too?<br></blockquote><div><br></div><div>Well, it still feels unnatural to me due to the definition of the boost (at least this much CPU b<span style="font-size:small;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">andwidth </span>but higher should be fine).</div><div>Say I have a task which normally has specific boost and clamp requirements (say TG.UCLAMP_MIN=20, <span style="font-size:small;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">TG.</span><span style="font-size:12.8px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">UCLAMP_MAX=80)</span> which I want to temporarily boost using a syscall to <span style="font-size:small;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">UCLAMP_MIN</span><span style="font-size:small;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">=60 (let's say </span>a process should handle some request and temporarily needs more CPU bandwidth). With this interface we can clamp more than <span style="font-size:small;text-decoration-style:initial;text-decoration-color:initial;background-color:rgb(255,255,255);float:none;display:inline">TG.</span><span style="text-decoration-style:initial;text-decoration-color:initial;font-size:12.8px;background-color:rgb(255,255,255);float:none;display:inline">UCLAMP_MAX</span> value but we can't boost more than <span style="font-size:small;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">TG.UCLAMP_MIN</span>. For this usecase I would have to set TG.<span style="font-size:small;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">UCLAMP_MIN</span><span style="font-size:small;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">=80, then use syscall to set SYSCALL<span style="text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">.</span><span style="text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">UCLAMP_MIN</span><span style="text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">=20 to get effective <span style="font-size:small;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">UCLAMP_MIN=20</span></span> and then set <span style="text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">SYSCALL</span><span style="text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">.</span><span style="text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">UCLAMP_MIN=60</span> when I need that temporary boost.</span></div><div><span style="font-size:small;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">To summarize, while this API does not stop me from achieving the desired result it requires some hoop-jumping :)</span></div><div> <br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> <br> I think the important bits are that we are all on the same page about<br> the end goals and features we like to have as well as the interface we use.<br> This last has to fits best our goals and features while still being<br> perfectly aligned with the frameworks we are integrating into... and<br> that's still under discussion with Tejun on PATCH 08/12.<br> <br> Thanks again for your review!<br> <br> Cheers Patrick<br> <div class="gmail-HOEnZb"><div class="gmail-h5"><br> -- <br> #include <best/regards.h><br> <br> Patrick Bellasi<br> </div></div></blockquote></div><br></div></div>
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