From dc6d2bc2d893a878e7b58578ff01b4738708deb4 Mon Sep 17 00:00:00 2001 From: Ian Rogers Date: Mon, 13 Jan 2025 11:43:45 -0800 Subject: perf sample: Make user_regs and intr_regs optional The struct dump_regs contains 512 bytes of cache_regs, meaning the two values in perf_sample contribute 1088 bytes of its total 1384 bytes size. Initializing this much memory has a cost reported by Tavian Barnes as about 2.5% when running `perf script --itrace=i0`: https://lore.kernel.org/lkml/d841b97b3ad2ca8bcab07e4293375fb7c32dfce7.1736618095.git.tavianator@tavianator.com/ Adrian Hunter replied that the zero initialization was necessary and couldn't simply be removed. This patch aims to strike a middle ground of still zeroing the perf_sample, but removing 79% of its size by make user_regs and intr_regs optional pointers to zalloc-ed memory. To support the allocation accessors are created for user_regs and intr_regs. To support correct cleanup perf_sample__init and perf_sample__exit functions are created and added throughout the code base. Signed-off-by: Ian Rogers Link: https://lore.kernel.org/r/20250113194345.1537821-1-irogers@google.com Signed-off-by: Namhyung Kim --- tools/perf/util/machine.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'tools/perf/util/machine.c') diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c index 321cc110698c..55d4977b9913 100644 --- a/tools/perf/util/machine.c +++ b/tools/perf/util/machine.c @@ -2909,8 +2909,8 @@ static int thread__resolve_callchain_unwind(struct thread *thread, return 0; /* Bail out if nothing was captured. */ - if ((!sample->user_regs.regs) || - (!sample->user_stack.size)) + if (!sample->user_regs || !sample->user_regs->regs || + !sample->user_stack.size) return 0; if (!symbols) -- cgit v1.2.3