<div dir="ltr">Hello all,<div><br></div><div style>I'm trying to check schedulability for simple HRT/SRT task sets using Litmus-rt 2014.2.</div><div style>* 8 Cores, no hyper-threading, 16G memory</div><div style>* Bare-metal testing, Ubuntu 12.04 (Linux 3.10.41)</div><div style>* rt_launch program, 20-30 seconds</div><div style><br></div><div style>On top of clean OS and litmus-rt, only rt_launch is running and then st-* trace files are recorded.</div><div style>I expected that all cases should be schedulable and c-edf result is better than g-edf result. </div><div style>(At least, if Utilization <= 70% then c-edf schedulability >= 0.8)</div><div style><br></div><div style>But, as shown in the first following table and the second graph (bare-metal litmus-rt), </div><div style>even w/ 45% CPUs utilization (6*(120,200)=3.6), the schedulability is dropped so much and c-edf result isn't better than g-edf case.<br></div><div style>The schedulability for c-edf and g-edf (6th and 7th column) is an averaged value (20 times).</div><div style><br></div><div style>Based on other related papers, I expected that the schedulability (c-edf) will be larger than 0.7~0.8 (at least) up to 74.4% utilization (5.95).</div><div style>But, HRT and SRT, both cases produced around 0.5 schedulability. </div><div style><br></div><div style>Even though I tried 1*(180,200) ~ 8*(180,200) as shown in the third graph, it's little bit better but still not good and fluctuation is happened.</div><div style>And, even though the utillization is similar, the schedulability is very different if the number of task sets is different.</div><div style><br></div><div style>Is this correct? How can I increase the schedulability? How can I see the difference between c-edf and g-edf?</div><div style>Is there anything that I should check for schedulability? Any tips to get best schedulability?</div><div><br></div><div>(1)</div><div>
<table border="0" cellpadding="0" cellspacing="0" width="467" style="border-collapse:collapse;width:467pt">
<colgroup><col width="65" span="4" style="width:65pt">
<col width="77" style="width:77pt">
<col width="65" span="2" style="width:65pt">
</colgroup><tbody><tr height="15" style="height:15pt">
<td height="15" class="" width="65" style="height:15pt;width:65pt">num-tasks</td>
<td class="" width="65" style="width:65pt">period</td>
<td class="" width="65" style="width:65pt">wcet</td>
<td class="" width="65" style="width:65pt">utilization</td>
<td class="" width="77" style="width:77pt">ratio</td>
<td class="" width="65" style="width:65pt">bm-c-edf</td>
<td class="" width="65" style="width:65pt">bm-g-edf</td>
</tr>
<tr height="15" style="height:15pt">
<td height="15" class="" style="height:15pt">4.00</td>
<td class="">200.00</td>
<td class="">60.00</td>
<td class="">1.20</td>
<td class="">15.0%</td>
<td class="">0.99</td>
<td class="">1.00</td>
</tr>
<tr height="15" style="height:15pt">
<td height="15" class="" style="height:15pt">4.00</td>
<td class="">200.00</td>
<td class="">100.00</td>
<td class="">2.00</td>
<td class="">25.0%</td>
<td class="">1.00</td>
<td class="">0.99</td>
</tr>
<tr height="15" style="height:15pt">
<td height="15" class="" style="height:15pt">5.00</td>
<td class="">200.00</td>
<td class="">110.00</td>
<td class="">2.75</td>
<td class="">34.4%</td>
<td class="">0.87</td>
<td class="">0.92</td>
</tr>
<tr height="15" style="height:15pt">
<td height="15" class="" style="height:15pt">6.00</td>
<td class="">200.00</td>
<td class="">120.00</td>
<td class="">3.60</td>
<td class="">45.0%</td>
<td class="">0.64</td>
<td class="">0.79</td>
</tr>
<tr height="15" style="height:15pt">
<td height="15" class="" style="height:15pt">6.00</td>
<td class="">200.00</td>
<td class="">145.00</td>
<td class="">4.35</td>
<td class="">54.4%</td>
<td class="">0.70</td>
<td class="">0.70</td>
</tr>
<tr height="15" style="height:15pt">
<td height="15" class="" style="height:15pt">7.00</td>
<td class="">200.00</td>
<td class="">150.00</td>
<td class="">5.25</td>
<td class="">65.6%</td>
<td class="">0.49</td>
<td class="">0.51</td>
</tr>
<tr height="15" style="height:15pt">
<td height="15" class="" style="height:15pt">7.00</td>
<td class="">200.00</td>
<td class="">170.00</td>
<td class="">5.95</td>
<td class="">74.4%</td>
<td class="">0.50</td>
<td class="">0.59</td>
</tr>
<tr height="15" style="height:15pt">
<td height="15" class="" style="height:15pt">7.00</td>
<td class="">200.00</td>
<td class="">180.00</td>
<td class="">6.30</td>
<td class="">78.8%</td>
<td class="">0.57</td>
<td class="">0.50</td>
</tr>
<tr height="15" style="height:15pt">
<td height="15" class="" style="height:15pt">7.00</td>
<td class="">200.00</td>
<td class="">190.00</td>
<td class="">6.65</td>
<td class="">83.1%</td>
<td class="">0.49</td>
<td class="">0.51</td>
</tr>
<tr height="15" style="height:15pt">
<td height="15" class="" style="height:15pt">8.00</td>
<td class="">200.00</td>
<td class="">180.00</td>
<td class="">7.20</td>
<td class="">90.0%</td>
<td class="">0.41</td>
<td class="">0.41</td>
</tr>
</tbody></table><br></div><div>(2)</div><div><img src="cid:ii_i0zel8q70_148eb3adbc96d0f4" width="509" height="306"><br></div><div><br></div><div>(3) 1*(180,200) ~ 8*(180,200)</div><div><img src="cid:ii_i0zie7le4_148eb9c5cf220778" width="508" height="270" style="margin-right: 0px; "><br><br></div><div><br></div><div style>Thanks,</div><div style>Mikyung</div><div><br></div></div>