Multiprocessor system is an interconnection of two or more CPUs with memory and input-output equipment
The components that forms multiprocessor are CPUs IOPs connected to input –output devices , and memory unit that may be partitioned into a number of separate modules.
Multiprocessor are classified as multiple instruction stream, multiple data stream (MIMD) system.
Multiprocessor system is an interconnection of two or more CPUs with memory and input-output equipment
The components that forms multiprocessor are CPUs IOPs connected to input –output devices , and memory unit that may be partitioned into a number of separate modules.
Multiprocessor are classified as multiple instruction stream, multiple data stream (MIMD) system.
Caches in multiprocessing environment introduce the Cache Coherence problem.
When multiple processors maintain locally cached copies of a unique shared memory location, any local modification of the location can result in a globally inconsistent view of memory. This is called Cache Coherence Problem.
A brief discussion about its solutions are given.
RISC - Reduced Instruction Set ComputingTushar Swami
A detailed presentation about what is RISC and some of the basic differences between RISC and CISC Computers.
Also enlisting some of the major applications of RISC in the field of Technology.
Caches in multiprocessing environment introduce the Cache Coherence problem.
When multiple processors maintain locally cached copies of a unique shared memory location, any local modification of the location can result in a globally inconsistent view of memory. This is called Cache Coherence Problem.
A brief discussion about its solutions are given.
RISC - Reduced Instruction Set ComputingTushar Swami
A detailed presentation about what is RISC and some of the basic differences between RISC and CISC Computers.
Also enlisting some of the major applications of RISC in the field of Technology.
This slide contain the description about the various technique related to parallel Processing(vector Processing and array processor), Arithmetic pipeline, Instruction Pipeline, SIMD processor, Attached array processor
Parallel computing is a type of computation in which many calculations or the execution of processes are carried out simultaneously. Large problems can often be divided into smaller ones, which can then be solved at the same time. There are several different forms of parallel computing: bit-level, instruction-level, data, and task parallelism. Parallelism has been employed for many years, mainly in high-performance computing, but interest in it has grown lately due to the physical constraints preventing frequency scaling. As power consumption (and consequently heat generation) by computers has become a concern in recent years, parallel computing has become the dominant paradigm in computer architecture, mainly in the form of multi-core processors.
The objectives of Multithreaded Programming in Operating Systems are:
- To introduce the notion of a thread—a fundamental unit of CPU utilization that forms the basis of multithreaded computer systems.
- To discuss the APIs for the Pthreads, Windows, and Java thread libraries
- To explore several strategies that provide implicit threading.
- To examine issues related to multithreaded programming.
- To cover operating system support for threads in Windows and Linux.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
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A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
2. Goal
Utilization of coarser-grained parallelism by CMPs and multithreaded processors
Focus is on processors that are designed to simultaneously execute threads of
same or different processes.(explicit multithreaded processors)
Explicit multithreaded processors aim is to increase the performance(low
execution time) of a multiprogramming workload, while single threaded/implicit
multithreaded and superscalar processors increase performance of single
program.
CMP – Chip Multiprocessor(2 or more processors on a single chip)
Multithreaded processors- interleaves execution of different threads of control in
the same pipeline.
3. What is it?
●Notion of thread
● Different from a software application thread
● coarse-grained thread-level parallelism
● Implies separate logical address space
●Implicit Multithreading
● Find multiple lines of execution in a single seq. program.
●Explicit multithreading
● Multiple PCs, register contexts
● Different from RISC processors
4. Why do we need it?
• ILP is limited
• Memory latency problem, covering up long latency cycles by useful work.
• Div and branch interlocking. Covering up idle time of CPU
• Latency: primary cache miss/2ndary cache miss
• Several enabled instructions from diff threads that may be candidates for
execution.
• Switching in a single threaded processor is costly!
• Idle hardware utilization
5. Multithreaded Processors –
Principle Approaches
●Techniques
● Fast context switch(how?)
●Interleaved multithreading technique
● Instruction from different threads every cycle
●Blocked multithreading technique
● Continues until an event occurs
●Simultaneous multithreading
● Simultaneously issue multiple instructions from multiple
threads(Superscalar)
6. Taken from [2]. Survey of processors with explicit multithreading.
7. Interleaved multithreading(fine-
grained)
• Processor switches to a different thread after each IF
• Context switch after every clock cycle
• Eliminates data and control hazards
• Improves overall performance(execution time)
• Requires at least as many threads as pipeline stages
• Single-thread performance degrades
• Two techniques to overcome this
• Dependence lookahead technique(CRAY MTA)
• Interleaving technique
8. CRAY MTA
• Interleaved multithreaded VLIW processor
• uses explicit look ahead technique
• 3 bits to encode
• Supports 128 distinct threads
• Hides memory latency
• VLIW
• 64 bit instructions consists of 3 operations
• <M-op, A-op, C-op>- priority from high to low
9. Blocked multithreading(coarse-
grained)
• Continues execution until a context switch is forced
• Single thread can proceed at full speed
• Lesser threads needed compared to interleaved multithreading
• Context switch events
• Switch-on-load
• Switch-on-store
• Switch-on-branch
• Switch-on-cache-miss
• Switch-on-signals(interrupts)
• Conditional switch
10. MIT Sparcle
• Context switch only during a remote cache miss
• Small latencies are taken care of by the compilers.
• Implementation of fast context switching
• Also uses multiple register contexts and PCs
11. Simultaneous multithreading(SMT)
• Mix of superscalar and multithreading technique
• All hardware contexts are active leading to competition
• Issue multiple instructions from multiple threads each cycle
• Both TLP and ILP comes into play
• Multiple slots for different threads are filled as well multiple
issue slots are filled.
• Resource organization
• Resource sharing
• Resource replication
12. SMT Alpha 21164 processor
• Simulations conducted on 8 threaded 8-issue
superscalar
• 3 Floating point units and 6 integer units are
assumed
• Fetch policy
• Throughput
• 6.64 IPC on SPEC92 benchmark
13. Taken from [2]. Survey of processors with explicit multithreading.
14. Comparison
Chip Multiprocessors
1. Multiple processors on a single
chip
2. Every unit is duplicated and
works independently
3. Latency problem remains in
multiple issue cycles.
4. Every part of a processor is
duplicated so easier to
implement.
Multithreaded Processors
1. Multithreading comes into play
2. multiple threads under execution
so multiple PCs and registers
3. Latencies arising in one stream
are filled by another thread unlike
RISC architectures.
4. Hardware either shared or
replicated so complex.
15. References
1. Theo Ungerer, Borut Robic and Jurij Silc.
(2002) Multithreaded Processors in The
Computer Journal, Vol. 45 No. 3.
2. Theo Ungerer, Borut Robic and Jurij Silc.
(2003) A survey of Processors with Explicit
Multithreading in ACM Computing Surveys, Vol.
35 No. 1, March 2003, pp. 29-63.
