kernel/linux.git/tools/perf/util/threads.h, branch v6.18.21

perf threads: Reduce table size from 256 to 8

2024-03-04T06:52:13+00:00

The threads data structure is an array of hashmaps, previously rbtrees. The two levels allows for a fixed outer array where access is guarded by rw_semaphores. Commit 91e467bc568f ("perf machine: Use hashtable for machine threads") sized the outer table at 256 entries to avoid future scalability problems, however, this means the threads struct is sized at 30,720 bytes. As the hashmaps allow O(1) access for the common find/insert/remove operations, lower the number of entries to 8. This reduces the size overhead to 960 bytes. Signed-off-by: Ian Rogers Acked-by: Namhyung Kim Cc: Yang Jihong Cc: Oliver Upton Signed-off-by: Namhyung Kim Link: https://lore.kernel.org/r/20240301053646.1449657-8-irogers@google.com

perf threads: Switch from rbtree to hashmap

2024-03-04T06:52:04+00:00

The rbtree provides a sorting on entries but this is unused. Switch to using hashmap for O(1) rather than O(log n) find/insert/remove complexity. Signed-off-by: Ian Rogers Acked-by: Namhyung Kim Cc: Yang Jihong Cc: Oliver Upton Signed-off-by: Namhyung Kim Link: https://lore.kernel.org/r/20240301053646.1449657-7-irogers@google.com

perf threads: Move threads to its own files

2024-03-04T06:51:55+00:00

Move threads out of machine and into its own file. Signed-off-by: Ian Rogers Acked-by: Namhyung Kim Cc: Yang Jihong Cc: Oliver Upton Signed-off-by: Namhyung Kim Link: https://lore.kernel.org/r/20240301053646.1449657-6-irogers@google.com