Re: [PATCH v2 0/7] Add io_dir to avoid memory overhead from opendir
From: Namhyung Kim
Date: Wed Feb 19 2025 - 16:55:35 EST
On Fri, Feb 07, 2025 at 03:24:41PM -0800, Ian Rogers wrote:
> glibc's opendir allocates a minimum of 32kb, when called recursively
> for a directory tree the memory consumption can add up - nearly 300kb
> during perf start-up when processing modules. Add a stack allocated
> variant of readdir sized a little more than 1kb
>
> v2: Remove the feature test and always use a perf supplied getdents64
> to workaround an Alpine Linux issue in v1:
> https://lore.kernel.org/lkml/20231207050433.1426834-1-irogers@xxxxxxxxxx/
> As suggested by Krzysztof Łopatowski
> <krzysztof.m.lopatowski@xxxxxxxxx> who also pointed to the perf
> trace performance improvements in start-up time eliminating stat
> calls can achieve:
> https://lore.kernel.org/lkml/20250206113314.335376-2-krzysztof.m.lopatowski@xxxxxxxxx/
Let me pick up Krzysztof's patch first.
Thanks,
Namhyung
> Convert parse-events and hwmon_pmu to use io_dir.
> v1: This was previously part of the memory saving change set:
> https://lore.kernel.org/lkml/20231127220902.1315692-1-irogers@xxxxxxxxxx/
> It is separated here and a feature check and syscall workaround
> for missing getdents64 added.
>
> Ian Rogers (7):
> tools lib api: Add io_dir an allocation free readdir alternative
> perf maps: Switch modules tree walk to io_dir__readdir
> perf pmu: Switch to io_dir__readdir
> perf header: Switch mem topology to io_dir__readdir
> perf events: Remove scandir in thread synthesis
> perf parse-events: Switch tracepoints to io_dir__readdir
> perf hwmon_pmu: Switch event discovery to io_dir__readdir
>
> tools/lib/api/Makefile | 2 +-
> tools/lib/api/io_dir.h | 91 ++++++++++++++++++++++++++++++
> tools/perf/util/header.c | 31 +++++-----
> tools/perf/util/hwmon_pmu.c | 42 ++++++--------
> tools/perf/util/machine.c | 19 +++----
> tools/perf/util/parse-events.c | 32 ++++++-----
> tools/perf/util/pmu.c | 46 +++++++--------
> tools/perf/util/pmus.c | 30 ++++------
> tools/perf/util/synthetic-events.c | 22 ++++----
> 9 files changed, 194 insertions(+), 121 deletions(-)
> create mode 100644 tools/lib/api/io_dir.h
>
> --
> 2.48.1.502.g6dc24dfdaf-goog
>