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<DIV>Thank you very much for your help! I am interested in that implementation.
I will appreciate that if you can share it to me.</DIV>
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<DIV> </DIV>
<DIV style="FONT-SIZE: 10pt; FONT-FAMILY: Verdana; COLOR: #c0c0c0"
align=left>2016-08-30
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<SPAN id=_FlashSignName>shijunjie92</SPAN> </DIV>
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<DIV><STRONG>发件人：</STRONG>Björn Brandenburg <bbb@mpi-sws.org></DIV>
<DIV><STRONG>发送时间：</STRONG>2016-08-30 19:13</DIV>
<DIV><STRONG>主题：</STRONG>Re: [LITMUS^RT] Synchronization of resources</DIV>
<DIV><STRONG>收件人：</STRONG>"litmus-dev"<litmus-dev@lists.litmus-rt.org></DIV>
<DIV><STRONG>抄送：</STRONG></DIV>
<DIV> </DIV>
<DIV><BR>
<DIV>
<BLOCKQUOTE type="cite">
<DIV>On 30 Aug 2016, at 20:00, shijunjie92 <<A
href="mailto:shijunjie92@gmail.com">shijunjie92@gmail.com</A>>
wrote:</DIV><BR class=Apple-interchange-newline>
<DIV>
<DIV
style="FONT-SIZE: 14px; FONT-FAMILY: 'times new roman'; WHITE-SPACE: normal; WORD-SPACING: 0px; TEXT-TRANSFORM: none; FONT-WEIGHT: normal; FONT-STYLE: normal; LETTER-SPACING: normal; TEXT-INDENT: 0px; font-variant-caps: normal; -webkit-text-stroke-width: 0px">The
reason why I ask the last question is that I am trying to implement the
'help mechanism' of MrsP.</DIV></DIV></BLOCKQUOTE>
<DIV><BR></DIV>
<DIV>I haven’t tried implementing the MrsP myself, so I can’t really offer
much specific guidance here.</DIV><BR>
<BLOCKQUOTE type="cite">
<DIV
style="FONT-SIZE: 14px; FONT-FAMILY: 'times new roman'; WHITE-SPACE: normal; WORD-SPACING: 0px; TEXT-TRANSFORM: none; FONT-WEIGHT: normal; FONT-STYLE: normal; LETTER-SPACING: normal; TEXT-INDENT: 0px; font-variant-caps: normal; -webkit-text-stroke-width: 0px">The
resource-holding task can be preempted by other higher priority normal
execution task, but it still holds the resource. So I need to find out, is
there any task in other processor is spinning and waitting for that
resource. Sothat this processor can do the 'help'. Of cource, such task have
been enqueued on the wait queue of that semaphore. But how can I locate that
task when it locates on the middle of that queue?(traverse all the wait
queue and compare to all the processors' spinning
tasks?)</DIV></BLOCKQUOTE></DIV><BR>
<DIV>Good questions. These are exactly the kind of problems why “helping” and
“migrate-on-blocking” policies are difficult to implement in a real OS, even
though they look very appealing on paper. </DIV>
<DIV><BR></DIV>
<DIV>For what it's worth, my MC-IPC implementation requires multiprocessor
bandwidth inheritance, which runs into similar problems. It’s not part of
the LITMUS^RT mainline version, but if you are interested I can share a
version (that hasn’t been cleaned up yet) with you off list. (Of course, you’d
get it as it is, no support implied, etc.)</DIV>
<DIV><BR></DIV>
<DIV>- Björn</DIV>
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