From c658045197814b7d762662f9aa9f652379121a03 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Wed, 30 Apr 2014 15:47:27 +0200 Subject: [PATCH] perf tools: Cache dso data file descriptor Caching dso data file descriptors to avoid expensive re-opens especially during DWARF unwind. We keep dsos data file descriptors open until their count reaches the half of the current fd open limit (RLIMIT_NOFILE). In this case we close file descriptor of the first opened dso object. We've got overall speedup (~27% for my workload) of report: 'perf report --stdio -i perf-test.data' (3 runs) (perf-test.data size was around 12GB) current code: 545,640,944,228 cycles ( +- 0.53% ) 785,255,798,320 instructions ( +- 0.03% ) 366.340910010 seconds time elapsed ( +- 3.65% ) after change: 435,895,036,114 cycles ( +- 0.26% ) 636,790,271,176 instructions ( +- 0.04% ) 266.481463387 seconds time elapsed ( +- 0.13% ) Acked-by: Namhyung Kim Cc: Arnaldo Carvalho de Melo Cc: Corey Ashford Cc: David Ahern Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Jean Pihet Cc: Namhyung Kim Cc: Paul Mackerras Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/1401892622-30848-7-git-send-email-jolsa@kernel.org Signed-off-by: Jiri Olsa --- tools/perf/util/dso.c | 61 +++++++++++++++++++++++++++++- tools/perf/util/unwind-libunwind.c | 2 - 2 files changed, 59 insertions(+), 4 deletions(-) diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c index 76e5c13afc8f..fbf6cc98b8a9 100644 --- a/tools/perf/util/dso.c +++ b/tools/perf/util/dso.c @@ -1,4 +1,6 @@ #include +#include +#include #include "symbol.h" #include "dso.h" #include "machine.h" @@ -180,12 +182,20 @@ static int __open_dso(struct dso *dso, struct machine *machine) return fd; } +static void check_data_close(void); + static int open_dso(struct dso *dso, struct machine *machine) { int fd = __open_dso(dso, machine); - if (fd > 0) + if (fd > 0) { dso__list_add(dso); + /* + * Check if we crossed the allowed number + * of opened DSOs and close one if needed. + */ + check_data_close(); + } return fd; } @@ -204,6 +214,54 @@ static void close_dso(struct dso *dso) close_data_fd(dso); } +static void close_first_dso(void) +{ + struct dso *dso; + + dso = list_first_entry(&dso__data_open, struct dso, data.open_entry); + close_dso(dso); +} + +static rlim_t get_fd_limit(void) +{ + struct rlimit l; + rlim_t limit = 0; + + /* Allow half of the current open fd limit. */ + if (getrlimit(RLIMIT_NOFILE, &l) == 0) { + if (l.rlim_cur == RLIM_INFINITY) + limit = l.rlim_cur; + else + limit = l.rlim_cur / 2; + } else { + pr_err("failed to get fd limit\n"); + limit = 1; + } + + return limit; +} + +static bool may_cache_fd(void) +{ + static rlim_t limit; + + if (!limit) + limit = get_fd_limit(); + + if (limit == RLIM_INFINITY) + return true; + + return limit > (rlim_t) dso__data_open_cnt; +} + +static void check_data_close(void) +{ + bool cache_fd = may_cache_fd(); + + if (!cache_fd) + close_first_dso(); +} + void dso__data_close(struct dso *dso) { close_dso(dso); @@ -356,7 +414,6 @@ dso_cache__read(struct dso *dso, struct machine *machine, if (ret <= 0) free(cache); - dso__data_close(dso); return ret; } diff --git a/tools/perf/util/unwind-libunwind.c b/tools/perf/util/unwind-libunwind.c index 4f8dd9ee3899..25578b98f5c5 100644 --- a/tools/perf/util/unwind-libunwind.c +++ b/tools/perf/util/unwind-libunwind.c @@ -250,7 +250,6 @@ static int read_unwind_spec_eh_frame(struct dso *dso, struct machine *machine, /* Check the .eh_frame section for unwinding info */ offset = elf_section_offset(fd, ".eh_frame_hdr"); - dso__data_close(dso); if (offset) ret = unwind_spec_ehframe(dso, machine, offset, @@ -271,7 +270,6 @@ static int read_unwind_spec_debug_frame(struct dso *dso, /* Check the .debug_frame section for unwinding info */ *offset = elf_section_offset(fd, ".debug_frame"); - dso__data_close(dso); if (*offset) return 0; -- 2.20.1