May 30, 2016
Here are some of the performance at ITEC Dinner and sorry for the quality of the video. P/s: the red shirt guy is my senior Luqman haha
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Here are some of the performance at ITEC Dinner and sorry for the quality of the video. P/s: the red shirt guy is my senior Luqman haha
Missing one person which is Bella and the rest are awesome!
Dinner ITEC 2016.
Location : N'dah Hall, Shah Alam. Date: 25th May 2016 Time: 8.30 PM - 11.30 PM
Supposed it's a celebration pre-graduation dinner for seniors only but since the president of our club said "IT'S A COMPULSORY FOR PART 3 STUDENT TO JOIN THE EVENT!" anddd we here to celebrate part 6 senior of our course. The cost that we paid around RM50 and all my classmates were like "Wow, why it's soo expensive I mean like back then from our campus, we didn't have to pay at all! *with angry faces* " Well from my campus Jasin, to pay for dinner fee sometimes exceed RM50 so we didn't even surprise if we have to pay it that much cost. And so at the beginning of the dinner, it's quite boring and only our class for part 3 had attended this event. It's kinda awkward because we don't even recognise the seniors and so do they. So no conversation with the seniors, at all. We just talked among our class, take some pictures and "syok sendiri" hahaha. But i mean not every senior I don't recognise, I know Luqmanul Hakim a.k.a Bob haha, since he's my senior from SM Teknik Shah Alam and we even from the same course. I didn't know that he's so famous here because back then he's just a quiet person. Well, time changes people.
Nevermind about that, so the theme for that event is magical and not any one of us follows the theme because it's a last minute participation and we don't have time to find ourselves nice pieces of clothes that suit the theme. So we just go for the proper attire as long as we attend the dinner and we can eat! Hahaha the food is sooooooo worth the RM50 that we paid and it's mouthwatering and delicious like we go to eat at the tomyam restaurant. While we have the dinner, we've been entertained with some videos and performances from our senior and a lecturer. Seriously, most of them are hilarious. I can't imagine how the lecturers handle them in class hahaha.The event finished late almost at midnight and we were soo tired since the next day we had a test and I'm not ready for it. Huhh but at least I had fun that night yeayy!
Singularity: Verification
Heap memory safety
All local pointers point to the SIP’s heap
Pointers only come from SIP’s trusted memory allocator
Pointers are strongly typed
Exchange heap memory safety
EH pointers obey linear type discipline
No double access
Strongly typed
Channel contract agreement
Need to verify that both ends of a channel agree on the channel contract
Kernel ABI agreement
Instruction safety: can’t use privileged instructions inappropriately.
Channel contracts checked for unhanded messages
Channel contracts need all cycles in contract states to contain at least one receive and one send action.
Basically avoid A sending infinite messages to B without waiting for response. This can overflow buffer.
At SIP install time, verifier checks the byte code (byte code in MSIL).
Bytecode is machine-agnostic. Easier to verify.
Singularity: Exchange Heaps
Alternatives: message copying or kernel buffering. Performance not a convincing reason to use exchange heaps—micro benchmarks != application performance.
Kernel responsible for managing the exchange heap’s memory:
It GC’s the exchange heap to eliminate objects held by exited SIPs.
Singularity also prevents processes from simultaneously accessing objects in shared memory.
Exchange heap explicitly designed for IPC.
Linear type discipline for exchange heap objects.
Each process can have at most one pointer to an exchange heap object at a time. When a process sends a message, the type of the send “system call” forces the sending process to lose that sole pointer to the message.
Each exchange heap object is accessible to at most one process at a time.
Facilitates explicit allocation and deallocation operations for exchange heap objects, new and delete, which quickly recycle unneeded exchange heap memory.
Singularity: Page-disjoint Heaps
Sing# is a garbage collected language
Each process has page-disjoint heap. Why?
No shared memory (easy verification)
Simple accounting: memory size == page count
Simple recovery after process exit. Just reclaim all pages for garbage collect.
Simplify experiments with address space designs. what?
Each process can run own GC.
Hardware Iso Levels in Singularity
Evaluating Hardware Isolation Levels
You can use Singularity to evaluate levels of hardware isolation:
No runtime checks (bounds checks, null pointer checks).
Physical memory: default Singularity; segmentation no paging.
Add 4KB Pages: turn on paging.
Add separate domain: separate duplicate page table for application process, context switches require register %lcr3.
Add ring 3: give application process user privilege. Context switches require protected control transfer (syscall/interrupts).
Full Microkernel: all drivers in own separate privilege domain.
SIPs in Singularity
Software Isolated Processes
Processes run in same address space as kernel, isolated by software only.
Why not use hardware? Performance (kernel crossings are expensive).
Don’t need hardware virtual memory if you have a memory-safe language. Hardware VM needs TLB. TLB has extra cost.
Colocate processes with kernel code in single privileged address space.