TY - GEN
T1 - First-class user-level threads
AU - Marsh, Brian D.
AU - Scott, Michael L.
AU - LeBlanc, Thomas J.
AU - Markatos, Evangelos P.
PY - 1991/12/1
Y1 - 1991/12/1
N2 - It is often desirable, for reasons of clarity, portability, and efficiency, to write parallel programs in which the number of processes is independent of the number of available processors. Several modern operating systems support more than one process in an address space, but the overhead of creating and synchronizing kernel processes can be high. Many runtime environments implement lightweight processes (threads) in user space, but this approach usually results in second-class status for threads, making it difficult or impossible to perform scheduling operations at appropriate times (e.g. when the current thread blocks in the kernel). In addition, a lack of common assumptions may also make it difficult for parallel programs or library routines that use dissimilar thread packages to communicate with each other, or to synchronize access to shared data.We describe a set of kernel mechanisms and conventions designed to accord first-class status to user-level threads, allowing them to be used in any reasonable way that traditional kernel-provided processes can be used, while leaving the details of their implementation to user-level code. The key features of our approach are (1) shared memory for asynchronous communication between the kernel and the user, (2) software interrupts for events that might require action on the part of a user-level scheduler, and (3) a scheduler interface convention that facilitates interactions in user space between dissimilar kinds of threads. We have incorporated these mechanisms in the Psyche parallel operating system, and have used them to implement several different kinds of user-level threads. We argue for our approach in terms of both flexibility and performance.
AB - It is often desirable, for reasons of clarity, portability, and efficiency, to write parallel programs in which the number of processes is independent of the number of available processors. Several modern operating systems support more than one process in an address space, but the overhead of creating and synchronizing kernel processes can be high. Many runtime environments implement lightweight processes (threads) in user space, but this approach usually results in second-class status for threads, making it difficult or impossible to perform scheduling operations at appropriate times (e.g. when the current thread blocks in the kernel). In addition, a lack of common assumptions may also make it difficult for parallel programs or library routines that use dissimilar thread packages to communicate with each other, or to synchronize access to shared data.We describe a set of kernel mechanisms and conventions designed to accord first-class status to user-level threads, allowing them to be used in any reasonable way that traditional kernel-provided processes can be used, while leaving the details of their implementation to user-level code. The key features of our approach are (1) shared memory for asynchronous communication between the kernel and the user, (2) software interrupts for events that might require action on the part of a user-level scheduler, and (3) a scheduler interface convention that facilitates interactions in user space between dissimilar kinds of threads. We have incorporated these mechanisms in the Psyche parallel operating system, and have used them to implement several different kinds of user-level threads. We argue for our approach in terms of both flexibility and performance.
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U2 - 10.1145/121132.344329
DO - 10.1145/121132.344329
M3 - Conference contribution
AN - SCOPUS:0011611820
SN - 0897914473
SN - 9780897914475
T3 - Proceedings of the 13th ACM Symposium on Operating Systems Principles, SOSP 1991
SP - 110
EP - 121
BT - Proceedings of the 13th ACM Symposium on Operating Systems Principles, SOSP 1991
T2 - 13th ACM Symposium on Operating Systems Principles, SOSP 1991
Y2 - 13 October 1991 through 16 October 1991
ER -