b6a15269ce
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(), as io__getdelim(), 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@google.com> Acked-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Athira Jajeev <atrajeev@linux.vnet.ibm.com> Cc: Changbin Du <changbin.du@huawei.com> Cc: Colin Ian King <colin.i.king@gmail.com> Cc: Dmitrii Dolgov <9erthalion6@gmail.com> Cc: German Gomez <german.gomez@arm.com> Cc: Guilherme Amadio <amadio@gentoo.org> Cc: Huacai Chen <chenhuacai@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Clark <james.clark@arm.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: K Prateek Nayak <kprateek.nayak@amd.com> Cc: Kajol Jain <kjain@linux.ibm.com> Cc: Kan Liang <kan.liang@linux.intel.com> Cc: Leo Yan <leo.yan@linaro.org> Cc: Li Dong <lidong@vivo.com> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org> Cc: Miguel Ojeda <ojeda@kernel.org> Cc: Ming Wang <wangming01@loongson.cn> Cc: Nick Terrell <terrelln@fb.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ravi Bangoria <ravi.bangoria@amd.com> Cc: Sandipan Das <sandipan.das@amd.com> Cc: Sean Christopherson <seanjc@google.com> Cc: Steinar H. Gunderson <sesse@google.com> Cc: Vincent Whitchurch <vincent.whitchurch@axis.com> Cc: Wenyu Liu <liuwenyu7@huawei.com> Cc: Yang Jihong <yangjihong1@huawei.com> Link: https://lore.kernel.org/r/20231127220902.1315692-5-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.