[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <CAM9d7chgQBGMmyDyi98OUzyJHWaNUfw34VD=pStkX_n-t5Vpkg@mail.gmail.com>
Date: Sun, 5 Nov 2023 19:53:00 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: 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>,
Nick Terrell <terrelln@...com>,
Kan Liang <kan.liang@...ux.intel.com>,
Andi Kleen <ak@...ux.intel.com>,
Kajol Jain <kjain@...ux.ibm.com>,
Athira Rajeev <atrajeev@...ux.vnet.ibm.com>,
Huacai Chen <chenhuacai@...nel.org>,
Masami Hiramatsu <mhiramat@...nel.org>,
Vincent Whitchurch <vincent.whitchurch@...s.com>,
"Steinar H. Gunderson" <sesse@...gle.com>,
Liam Howlett <liam.howlett@...cle.com>,
Miguel Ojeda <ojeda@...nel.org>,
Colin Ian King <colin.i.king@...il.com>,
Dmitrii Dolgov <9erthalion6@...il.com>,
Yang Jihong <yangjihong1@...wei.com>,
Ming Wang <wangming01@...ngson.cn>,
James Clark <james.clark@....com>,
K Prateek Nayak <kprateek.nayak@....com>,
Sean Christopherson <seanjc@...gle.com>,
Leo Yan <leo.yan@...aro.org>,
Ravi Bangoria <ravi.bangoria@....com>,
German Gomez <german.gomez@....com>,
Changbin Du <changbin.du@...wei.com>,
Paolo Bonzini <pbonzini@...hat.com>, Li Dong <lidong@...o.com>,
Sandipan Das <sandipan.das@....com>,
liuwenyu <liuwenyu7@...wei.com>, linux-kernel@...r.kernel.org,
linux-perf-users@...r.kernel.org
Subject: Re: [PATCH v4 06/53] tools api fs: Switch filename__read_str to use io.h
On Thu, Nov 2, 2023 at 10:58 AM Ian Rogers <irogers@...gle.com> wrote:
>
> filename__read_str has its own string reading code that allocates
> memory before reading into it. The memory allocated is sized at BUFSIZ
> that is 8kb. Most strings are short and so most of this 8kb is
> wasted.
>
> Refactor io__getline so that the newline character can be configurable
> and ignored in the case of filename__read_str.
>
> Code like build_caches_for_cpu in perf's header.c will read many
> strings and hold them in a data structure, in this case multiple
> strings per cache level per CPU. Using io.h's io__getline avoids the
> wasted memory as strings are temporarily read into a buffer on the
> stack before being copied to a buffer that grows 128 bytes at a time
> and is never sized larger than the string.
>
> For a 16 hyperthread system the memory consumption of "perf record
> true" is reduced by 180kb, primarily through saving memory when
> reading the cache information.
>
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
[SNIP]
> diff --git a/tools/lib/api/io.h b/tools/lib/api/io.h
> index a77b74c5fb65..50d33e14fb56 100644
> --- a/tools/lib/api/io.h
> +++ b/tools/lib/api/io.h
> @@ -141,7 +141,7 @@ static inline int io__get_dec(struct io *io, __u64 *dec)
> }
>
> /* Read up to and including the first newline following the pattern of getline. */
You may want to update the comment as well.
> -static inline ssize_t io__getline(struct io *io, char **line_out, size_t *line_len_out)
> +static inline ssize_t io__getline_nl(struct io *io, char **line_out, size_t *line_len_out, int nl)
How about io__getdelim() similar to POSIX?
Thanks,
Namhyung
> {
> char buf[128];
> int buf_pos = 0;
> @@ -151,7 +151,7 @@ static inline ssize_t io__getline(struct io *io, char **line_out, size_t *line_l
>
> /* TODO: reuse previously allocated memory. */
> free(*line_out);
> - while (ch != '\n') {
> + while (ch != nl) {
> ch = io__get_char(io);
>
> if (ch < 0)
> @@ -184,4 +184,9 @@ static inline ssize_t io__getline(struct io *io, char **line_out, size_t *line_l
> return -ENOMEM;
> }
>
> +static inline ssize_t io__getline(struct io *io, char **line_out, size_t *line_len_out)
> +{
> + return io__getline_nl(io, line_out, line_len_out, /*nl=*/'\n');
> +}
> +
> #endif /* __API_IO__ */
> --
> 2.42.0.869.gea05f2083d-goog
>
Powered by blists - more mailing lists