linux-kernel - Re: [PATCH v3 0/8] Add io_dir to avoid memory overhead from opendir

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Message-Id: <174052069088.518612.8243648115065735498.b4-ty@kernel.org>
Date: Tue, 25 Feb 2025 13:58:10 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
 Arnaldo Carvalho de Melo <acme@...nel.org>, 
 Mark Rutland <mark.rutland@....com>, 
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>, 
 Jiri Olsa <jolsa@...nel.org>, Adrian Hunter <adrian.hunter@...el.com>, 
 Kan Liang <kan.liang@...ux.intel.com>, Sam James <sam@...too.org>, 
 Jesper Juhl <jesperjuhl76@...il.com>, James Clark <james.clark@...aro.org>, 
 Zhongqiu Han <quic_zhonhan@...cinc.com>, 
 Yicong Yang <yangyicong@...ilicon.com>, 
 Thomas Richter <tmricht@...ux.ibm.com>, Michael Petlan <mpetlan@...hat.com>, 
 Anne Macedo <retpolanne@...teo.net>, 
 Dominique Martinet <asmadeus@...ewreck.org>, 
 Jean-Philippe Romain <jean-philippe.romain@...s.st.com>, 
 Junhao He <hejunhao3@...wei.com>, linux-kernel@...r.kernel.org, 
 linux-perf-users@...r.kernel.org, 
 Krzysztof Łopatowski <krzysztof.m.lopatowski@...il.com>, 
 Ian Rogers <irogers@...gle.com>
Subject: Re: [PATCH v3 0/8] Add io_dir to avoid memory overhead from
 opendir

On Fri, 21 Feb 2025 22:10:05 -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
> 
> v3: Rebase on top of Krzysztof Łopatowski's work. Add additional
>     defines for SYS_getdents64 on all other architectures if its
>     definition is missing. Add a patch to further reduce the
>     stack/memory usage in machine__set_modules_path_dir by appending
>     to a buffer rather than creating a copy.
> 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@google.com/
>     As suggested by Krzysztof Łopatowski
>     <krzysztof.m.lopatowski@...il.com> 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@gmail.com/
>     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@google.com/
>     It is separated here and a feature check and syscall workaround
>     for missing getdents64 added.
> 
> [...]
Applied to perf-tools-next, thanks!

Best regards,
Namhyung