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Question	Answer
Compaction ist eine Lösung für das Problem external fragmentation	TRUE
Eine Seitentabelle hilft beim Übersetzten von physischen Adressen in virtuelle Adressen	FALSE
Der Hauptvorteil einer zweistufigen Seitentabelle gegenüber einer einstufigen ist, dass die zweistufige nicht vollständig im Hauptspeicher gehalten werden muss	(TRUE ?) The primary advantage of multilevel page tables: the amount of memory needed for the page table is not dictated by the size of the address space, but by the amount of memory that the process is using.
Eine Inode ist ein Eintrag in einem Unix Dateisystem, der einer Datei eindeutig zugeordnet ist	TRUE
Jeder Thread hat seinen eigenen (virtuellen) Registersatz	TRUE
Einen Deadlock kann man auch durch inkorrekte Verwendung von Semaphoren erzeugen	TRUE
Der Kernel-Mode ist ein Modus des Betriebssystems	FALSE (der CPU)
In der Intel-Architektur enthält das CR3-Register die Startadresse der Segmenttabelle	/
Relocation can be implemented using base/limit registers	TRUE
Virtual Memory can be implemented using software only	FALSE
The used bit and the dirty bit cannot both be set to 1	FALSE
The ELF format is a format for storing Exended Long Files	FALSE
Adding more memory to a computer will make it seem to "run faster"	TRUE
There is no such thing as "address space layout randomization"	FALSE
Thrashing in a virtual memory system is caused by too many processes not having their working set resident in memory	TRUE
The return value of a successful exec()-system call is always > 0	FALSE A successful exec()-system call never returns
Global variables are not shared accross multiple threads belonging to the same process	FALSE
Starvation is the case when a thread can never aquire a lock on a critical section	TRUE
A smaller page size leads to more TLB misses	FALSE
Whenever a thread reference a part of the virtual address space that is not currently loaded in the primary memory, the OS suspends execution and loads the missing information from another portion of primary memory	(FALSE ?)
A thread should always be able to distinguish between being temporarily blocked and deadlocked	FALSE
Early in his career, Elvis Presley was told: "Stick with driving a truck, because you'll never make it as a singer"	TRUE
It is possible for multithreading to improve the performance of an application in a single CPU system	TRUE
In general, there are more inodes than directories on a linux-file-system	TRUE
The use of a TLB eliminates the need for keeping a page table in memory	FALSE
Disabling Interrupts is no solution for ensuring mutual exclusion in user space	TRUE
The term "monitor" has nothing to do with operating systems beyond the fact that it is used to display stuff on it	FALSE
To wait on something inside monitor, condition variables are available	TRUE
The state of a thread changes from READY to RUNNING when the thread has been ready long enough	FALSE Image: 1 (binary/octet-stream)
The state of a thread never changes from READY to BLOCKED	TRUE Image: 1 (binary/octet-stream)
A MIPS processor does not use page tables	TRUE Software-filled TLB instead of page tables
When using the page-tables method: if linear address A is higher than linear address B, the physical address of A is not necessarily higher than the physical address of B	TRUE
When threads are implemented in kernel space, we do not need to switch the memory configuration when switching between two threads of the same process	TRUE
Ensuring mutal exclusion in critical sections is a way to get rid of the race condition problem	TRUE
With the Test-and-Set-Lock-instruction one can implement an atomic operation	/
Copy On Write is a principle that speeds up the process creation	TRUE
The OS resets the used bit (to 0)	TRUE
An operation that cannot be interrupted is called atomic	TRUE
It takes more effort to create a new thread than to create a new process	FALSE
A memory management unit is responsible for managing the user space memory	FALSE
CPU utilization tends to be higher when there are more processes in memory	TRUE
"Safe state" means that it is unlikely a deadlock will occur	FALSE
A virtual address consists of a page frame number, a page table number and a page size	FALSE
In contrast to a single-level page table, multilevel page tables result in slower page table lookups	TRUE
Multilevel page tables allow processes to share regions of memory while single-level page tables do not	FALSE
Page-based virtual memory is subject to external fragmentation	FALSE External fragmentation is the various free spaced holes that are generated in either your memory or disk space.
In a conventional paging system, a page table entry (PTE) will not contain an illegal-page bit	TRUE
The page number in the 24-bit address 0xABCDEF with an 512-byte page size is 0xABC	FALSE
Semaphore operations need to be atomic to guarantee mutal exclusion	TRUE
A TLB miss will cause a page fault to occur	FALSE
A process executes faster when running in kernel mode than when running in user mode	FALSE
Because of page-base virtual memory, operating systems never need to worry about allocating contiguous pages	TRUE
Switching among threads in the same process is more efficient than switching among processes	(TRUE ?)
A clock page replacement algorithm tries to approximate a Least Recently Used (LRU) algorithm	TRUE
Adding more memory to a computer will make it seem to "run faster"	TRUE
With paging the operating system can place any page of any process to any page frame in physical memory	TRUE
The page table is set up by the MMU	FALSE
The dirty bit is set by the operating system	FALSE by the hardware
Using mutual exclusion ensures that the system avoids deadlock	(FALSE ?)
The MMU resets the used bit (to 0)	(FALSE ?)
The POSIX execv() system call creates a new process	(FALSE ?) The exec() family of functions replaces the current process image with a new process image.
The operating system can (more or less) freely decide where in the virtual address space the stacl(s) are located	TRUE
There is no such thing as "address space layout randomization"	FALSE
There is no such thing as "address space layout duplication"	TRUE
With 64 bit addresses, only 48 bits are supported in current hardware	TRUE
Each page table needs to have within it a reference to each page frame in the system	FALSE
The base/limit register method provides relocation and protection	(TRUE ?)
The present bit is set by the MMU	FALSE
The accessed bit and the dirty bit cannot both be set to 1	FALSE
Single-level page tables allow processes to share regions of memory while multilevel page tables do not	FALSE
Multilevel page tables are used because they allow to translate multiple levels of addresses in parallel	FALSE
In a conventional paging system, a page table entry (PTE) will not contain the age of the page	TRUE
Page-based virtual memory is subject to internal fragmentation	TRUE
When a thread can never acquire a lock on a critical section we call that "starviation"	TRUE
For a machine with 32-bit addresses, the use of a two level page table allows for a larger virtual address space than a single level page table	FALSE
Two-phase locking is a mechanism that prevents deadlock in database systems	TRUE
Ignoring the deadlock-problem is a reasonable approach for a general purpose operating system	TRUE
Potential deadlock involving preemtable resources can be solved by reallocation	TRUE
When a process supports EPT (Extended Page Table), it is able to handle the guest- and the host page table simultaneously	TRUE
When a VMM does binary translation, it continuously reads program code before it is executed, looks for relevant commands and changes them on the fly	(TRUE ?)
The Virtual-Machine-Concept was invented around 2003	FALSE
On a classical UNIX-System, an inode contains all the information on a file	FALSE
The inode link-count indicates how often a file is referenced within the file-system	TRUE A link count telling how many hard links point to the inode
A logical journal writes only metadata into the journal	TRUE
The cow-concept is also used in file-systems	TRUE
A critical section is a piece of code which, when concurrently executed by multiple threads, may produce results that depend on the order these threads are executed	TRUE
When a user program is running, the CPU will be in supervisor mode since it is supervising the program	FALSE
A successful exec()-system call never returns	TRUE
All threads of a process share single address space	TRUE
A critical section is any piece of code that is protected by a mutex	FALSE
The TWELVE format is a format for storing binary programms	FALSE
User Mode and Kernel (or Supervisor) Mode are two modes of operation of a processor	TRUE
Since there is only one operating system running, there are no concurrency issues in operating system code	FALSE
One cannot implement monitors using semaphores	FALSE (One can not implement semaphores using monitors = TRUE)
A smaller page size leads to smaller page tables	FALSE
Get the cosine of a number is best implemented as a system call	FALSE
Semaphore are a good method to prevent deadlocks	FALSE
The dirty bit is set by the MMU	FALSE
A memory management unit translates virtual to physical addresses	TRUE
The MMU resets the accessed bit when the page has not been accessed for a while	FALSE
Address space layout randomization is meant to improve security	TRUE Address space layout randomization (ASLR) is a memory-protection process for operating systems (OSes) that guards against buffer-overflow attacks by randomizing the location where system executables are loaded into memory.
Each file in NTFS is represented by a variable-depth tree of extents	(TRUE ?)
In a COW file system, if we update a block, we write it and all the blocks on the path from it to the root to new locations	TRUE
FFS places data to optimize for the common case where a file's data blocks and meta data and different files from the same directory are accessed together	TRUE
The FAT file system lacks support for modern reliability technology	TRUE lack of modern reliability techniques
One cannot implement semaphores using monitors	TRUE
3072 cannot be a valid page size	TRUE
32 cannot be a valid page size	FALSE
A logical address of 0xA3213456 on a 32-bit page-based virtual memory system with 4KB pages has the offset 0x3456	FALSE 4KB pages - 12 bit offset -> offset would be 0x456
A monitor is one solution to solve the mutual exclusion problem	TRUE
A program containing a race condition will always result in data corruption or some other incorrect behavior	FALSE
A program containing a race condition will never result in data corruption or some other incorrect behavior	FALSE
A program containing a race condition will sometimes result in data corruption or some other incorrect behavior	TRUE
A race condition occurs when the outcome of processes is dependent on the exact order of execution among them.	TRUE
A race condition occurs when a process cannot make progress because another one is blocking it	FALSE
The working set model is used to compute the average number of frames a job will need in order to run smoothly without causing thrashing	FALSE
The FAT file system does not support hard links	TRUE No hard links
When the link count in an inode becomes 0, the file can be deleted	TRUE Inode link-count 0: - no more reference within file system - file can be deleted
In NTFS, the MFT contains at least one nonresident data attribute for each file	FALSE
In NTFS, a file may have multiple file name attributes	TRUE NTFS: File name and file number of parent directory may have multiple file name attributes (hard link)
COW file systems never overwrite existing data or metadata	TRUE
COW file systems perform better, because they gain from converting small random writes to large sequential ones	TRUE
A ZFS file-system is limited to one physical device	FALSE
Google, Amazon etc. estimate they lose 5%-10% of their customers if their response time increases by 100 milliseconds	TRUE
If tasks are equal in size, round robin schedule will have very good average response time	(FALSE ?)
A user-level process cannot modify its own page table entries	TRUE
By manipulating the assignment of tasks to priority queues, an MFQ scheduler can achieve a balance between responsiveness, low overhead and fairness	TRUE
The scheduler is the part of the operating system that determines the priority of each process	(FALSE ?)
A TLB is needed for correct execution of a program	FALSE
Each physical page belongs to only one process	FALSE
Every interrupt changes the CPU from user mode to kernel mode	TRUE
The VFS layer handles journalling for Very Large File Systems	FALSE virtual file system layer - interface allowing to use different file systems
Shortest Job First (SJF) or Shortest Completion Time First (SCTF) schedule is difficult to build on real operating systems	TRUE SJF Downsides: impossible to implement
The operating system has to reset the accessed bit when the page has not been accessed for a while	FALSE
The kernel is mapped into each user-level application process address space in order for applications to access the kernel's data conveniently	FALSE
In 32-bit x86 with paging turned on a machine instruction auch as "mov 0x02000000, %eax" could potentially involve three accesses to memory	(TRUE ?)
On x86, upon a TLB miss, the kernel traverses the 2-level page table to fill in the virtual to physical access mapping in the TLB	FALSE
Reading a random location in a big file is usually faster in an inode-based file-system than in a FAT file system	TRUE FAT: Poor random access -> need to traverse FAT
For better sequential read/write performance, a file system should try to allocate consecutive blocks to a file	(TRUE ?)
A guest OS kernel can't access the code and data of the VMM (such as the shadow page table)	(TRUE ?)
A hard link is indistinguishable from the original file itself	TRUE A hard link to a file is indistinguishable from the original name for the file; there's no particular link that is more the "real name" for the file than any other.
COW file systems overwrite metadata only	FALSE
System calls do not change the Fpriviledge-level of the processor	FALSE
In practice, all 64 bits are used with IA-64 addressing	FALSE
A physical address space is at least as large as a virtual address space	FALSE
A smaller page size leads to larger page tables	TRUE

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	Created by D P about 5 years ago