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| author | Ian Rogers <irogers@google.com> | 2025-01-13 22:43:45 +0300 |
|---|---|---|
| committer | Namhyung Kim <namhyung@kernel.org> | 2025-02-13 07:06:11 +0300 |
| commit | dc6d2bc2d893a878e7b58578ff01b4738708deb4 (patch) | |
| tree | b5524ff4429f1e88533f518753091462bc4bd8b4 /tools/perf/util/arm64-frame-pointer-unwind-support.c | |
| parent | 08d9e883481b2c38326ed37314b1f6a1284c03d8 (diff) | |
| download | linux-dc6d2bc2d893a878e7b58578ff01b4738708deb4.tar.xz | |
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 <tavianator@tavianator.com> as about 2.5% when running `perf
script --itrace=i0`:
https://lore.kernel.org/lkml/d841b97b3ad2ca8bcab07e4293375fb7c32dfce7.1736618095.git.tavianator@tavianator.com/
Adrian Hunter <adrian.hunter@intel.com> 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 <irogers@google.com>
Link: https://lore.kernel.org/r/20250113194345.1537821-1-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Diffstat (limited to 'tools/perf/util/arm64-frame-pointer-unwind-support.c')
| -rw-r--r-- | tools/perf/util/arm64-frame-pointer-unwind-support.c | 29 |
1 files changed, 18 insertions, 11 deletions
diff --git a/tools/perf/util/arm64-frame-pointer-unwind-support.c b/tools/perf/util/arm64-frame-pointer-unwind-support.c index 4940be4a0569..958afe8b821e 100644 --- a/tools/perf/util/arm64-frame-pointer-unwind-support.c +++ b/tools/perf/util/arm64-frame-pointer-unwind-support.c @@ -4,6 +4,7 @@ #include "event.h" #include "perf_regs.h" // SMPL_REG_MASK #include "unwind.h" +#include <string.h> #define perf_event_arm_regs perf_event_arm64_regs #include "../../arch/arm64/include/uapi/asm/perf_regs.h" @@ -16,8 +17,13 @@ struct entries { static bool get_leaf_frame_caller_enabled(struct perf_sample *sample) { - return callchain_param.record_mode == CALLCHAIN_FP && sample->user_regs.regs - && sample->user_regs.mask & SMPL_REG_MASK(PERF_REG_ARM64_LR); + struct regs_dump *regs; + + if (callchain_param.record_mode != CALLCHAIN_FP) + return false; + + regs = perf_sample__user_regs(sample); + return regs->regs && regs->mask & SMPL_REG_MASK(PERF_REG_ARM64_LR); } static int add_entry(struct unwind_entry *entry, void *arg) @@ -32,7 +38,7 @@ u64 get_leaf_frame_caller_aarch64(struct perf_sample *sample, struct thread *thr { int ret; struct entries entries = {}; - struct regs_dump old_regs = sample->user_regs; + struct regs_dump old_regs, *regs; if (!get_leaf_frame_caller_enabled(sample)) return 0; @@ -42,19 +48,20 @@ u64 get_leaf_frame_caller_aarch64(struct perf_sample *sample, struct thread *thr * and set its mask. SP is not used when doing the unwinding but it * still needs to be set to prevent failures. */ - - if (!(sample->user_regs.mask & SMPL_REG_MASK(PERF_REG_ARM64_PC))) { - sample->user_regs.cache_mask |= SMPL_REG_MASK(PERF_REG_ARM64_PC); - sample->user_regs.cache_regs[PERF_REG_ARM64_PC] = sample->callchain->ips[usr_idx+1]; + regs = perf_sample__user_regs(sample); + memcpy(&old_regs, regs, sizeof(*regs)); + if (!(regs->mask & SMPL_REG_MASK(PERF_REG_ARM64_PC))) { + regs->cache_mask |= SMPL_REG_MASK(PERF_REG_ARM64_PC); + regs->cache_regs[PERF_REG_ARM64_PC] = sample->callchain->ips[usr_idx+1]; } - if (!(sample->user_regs.mask & SMPL_REG_MASK(PERF_REG_ARM64_SP))) { - sample->user_regs.cache_mask |= SMPL_REG_MASK(PERF_REG_ARM64_SP); - sample->user_regs.cache_regs[PERF_REG_ARM64_SP] = 0; + if (!(regs->mask & SMPL_REG_MASK(PERF_REG_ARM64_SP))) { + regs->cache_mask |= SMPL_REG_MASK(PERF_REG_ARM64_SP); + regs->cache_regs[PERF_REG_ARM64_SP] = 0; } ret = unwind__get_entries(add_entry, &entries, thread, sample, 2, true); - sample->user_regs = old_regs; + memcpy(regs, &old_regs, sizeof(*regs)); if (ret || entries.length != 2) return ret; |