Changes between Initial Version and Version 1 of ALMPhDAbsEN

Timestamp:

May 9, 2014, 2:14:41 PM (10 years ago)

Author:

almaless

Comment:

--

ALMPhDAbsEN

@@ +1 @@
+Nowadays, single-chip cache-coherent many-core processors having up to 100 cores
+are a reality. Many-cores with hundreds or even a thousand of cores are planned 
+in the near future. In theses architectures, the question of the locality of L1 
+cache-miss related traffic (data, instruction and TLB) is essential for both 
+scalability and power consumption (energy by moved bit). Our thesis is that: 
+(i) handling the locality of memory accesses should be done at kernel level of 
+an operating system in a transparent manner to user applications; and (ii) the 
+current monolithic kernels are not able to enforce the locality of memory accesses 
+of multi-threaded applications, because the concept of thread in these kernels is 
+inherently unsuitable for many-core processors. Therefore, we believe that the 
+evolution approach of monolithic kernels undertaken until now is insufficient and 
+it is imperative to put the question of the locality of memory accesses in the 
+heart of this evolution.
+
+To prove our thesis, we designed and implemented ALMOS (Advanced Locality 
+Management Operating System), an experimental operating system based on a 
+distributed monolithic kernel. ALMOS has a new concept of thread, called Hybrid 
+Process. It allows its kernel to enforce the locality of memory accesses of each 
+thread. The resources (cores and physical memory) management in ALMOS's kernel is 
+distributed enforcing the locality of memory accesses when performing system 
+services. Decision making regarding memory allocation, tasks placement and load 
+balancing in ALMOS's kernel is decentralized, multi-criteria and without locking. 
+It is based on a distributed infrastructure coordinating, in a scalable manner, 
+the accesses to resources.
+
+Using the cycle accurate and bit accurate virtual prototype of TSAR many-core 
+processor, we experimentally demonstrated that: (i) performance (scalability and 
+execution time) on 256 cores of the distributed scheduling scheme of ALMOS's kernel 
+outperform those of the shared scheduling scheme found in existing monolithic 
+kernels; (ii) distributed realization of the fork system call enables this system 
+service to scale on 512 cores; (iii) updating the distrusted decision-making 
+infrastructure of ALMOS's kernel costs just 0.05 % of the total computing power of 
+TSAR processor; (iv) performance (scalability, execution time and remote traffic) 
+of memory affinity strategy of ALMOS's kernel, called Auto-Next-Touch, outperform 
+those of two existing strategies First-Touch and Interleave on 64 cores; (v) concept 
+of Hybrid Process of ALMOS's kernel scales up two existing highly multi-threads 
+applications on 256 cores and a third one on 1024 cores; and finally (vi) the couple 
+ALMOS/TSAR (64 cores) gives systematically much better scalability than the couple 
+Linux/AMD (Interlagos 64 cores) for 8 multi-threads applications belonging to HPC 
+and image processing domains.