liburcu用户空间的RCU实现介绍.pdfVIP

Userspace RCU Library: What Linear Multiprocessor Scalability Means for Your Application Linux Plumbers Conference 2009 Mathieu Desnoyers École Polytechnique de Montréal Mathieu Desnoyers ● Author/maintainer of : – LTTV (Linux Trace Toolkit Viewer) ● 2003-... – LTTng (Linux Trace Toolkit Next Generation) ● 2005-... – Immediate Values ● 2007... – Tracepoints ● 2008-... – Userspace RCU Library 2 ● 2009-... Contributions by ● Paul E. McKenney – IBM Linux Technology Center ● Alan Stern – Rowland Institute, Harvard University ● Jonathan Walpole – Computer Science Department, Portland State University ● Michel Dagenais – Computer and Software Engineering Dpt., 3 École Polytechnique de Montréal Summary ● RCU Overview ● Kernel vs Userspace RCU ● Userspace RCU Library ● Benchmarks ● RCU-Friendly Applications 4 Linux Kernel RCU Usage 5 RCU Overview ● Relativistic programming – Updates seen in different orders by CPUs – Tolerates conflicts ● Linear scalability ● Wait-free read-side ● Efficient updates – Only a single pointer exchange needs exclusive access 6 Schematic of RCU Update and Read-Side C.S. 7 RCU Linked-List Deletion 8 Kernel vs Userspace RCU ● Quiescent state – Kernel threads ● Wait for kernel pre-existing RCU read-side C.S. to complete – User threads ● Wait for process pre-existing RCU read-side C.S. to complete 9 Userspace RCU Library ● QSBR – liburcu-qsbr.so ● Generic RCU – liburcu-mb.so ● Signal-based RCU – liburcu.so ● call_rcu() – liburcu-defer.so 10 QSBR ● Detection of quiescent state: – E