Email Gateway (Aug 22 2022 at 18:55): Email Gateway (Aug 22 2022 at 18:55):From: Tobias Nipkow <nipkow@in.tum.de>
A Reduction Theorem for Store Buffers
Ernie Cohen and Norbert Schirmer
When verifying a concurrent program, it is usual to assume that memory is
sequentially consistent. However, most modern multiprocessors depend on store
buffering for efficiency, and provide native sequential consistency only at a
substantial performance penalty. To regain sequential consistency, a programmer
has to follow an appropriate programming discipline. However, na\"ive
disciplines, such as protecting all shared accesses with locks, are not flexible
enough for building high-performance multiprocessor software. We present a new
discipline for concurrent programming under TSO (total store order, with store
buffer forwarding). It does not depend on concurrency primitives, such as locks.
Instead, threads use ghost operations to acquire and release ownership of memory
addresses. A thread can write to an address only if no other thread owns it, and
can read from an address only if it owns it or it is shared and the thread has
flushed its store buffer since it last wrote to an address it did not own. This
discipline covers both coarse-grained concurrency (where data is protected by
locks) as well as fine-grained concurrency (where atomic operations race to
memory). We formalize this discipline in Isabelle/HOL, and prove that if every
execution of a program in a system without store buffers follows the discipline,
then every execution of the program with store buffers is sequentially
consistent. Thus, we can show sequential consistency under TSO by ordinary
assertional reasoning about the program, without having to consider store
buffers at all.
https://www.isa-afp.org/entries/Store_Buffer_Reduction.html
Enjoy ths first entry in 2019 (which goes back to 2010)
smime.p7s
Last updated: Nov 21 2024 at 12:39 UTC