From cd25f8bc2696664877b21d33b7994e12fa570919 Mon Sep 17 00:00:00 2001 From: Lin Ming Date: Fri, 25 Mar 2011 16:27:48 +0800 Subject: perf probe: Add fastpath to do lookup by function name v3 -> v2: - Make pubname_search_cb more generic - Add fastpath to find_probes also v2 -> v1: - Don't compare file names with cu_find_realpath(...), instead, compare them with the name returned by dwarf_decl_file(sp_die) The vmlinux file may have thousands of CUs. We can lookup function name from .debug_pubnames section to avoid the slow loop on CUs. 1. Improvement data for find_line_range ./perf stat -e cycles -r 10 -- ./perf probe -k /home/mlin/vmlinux \ -s /home/mlin/linux-2.6 \ --line csum_partial_copy_to_user > tmp.log before patch applied ===================== 847,988,276 cycles 0.355075856 seconds time elapsed after patch applied ===================== 206,102,622 cycles 0.086883555 seconds time elapsed 2. Improvement data for find_probes ./perf stat -e cycles -r 10 -- ./perf probe -k /home/mlin/vmlinux \ -s /home/mlin/linux-2.6 \ --vars csum_partial_copy_to_user > tmp.log before patch applied ===================== 848,490,844 cycles 0.355307901 seconds time elapsed after patch applied ===================== 205,684,469 cycles 0.086694010 seconds time elapsed Acked-by: Masami Hiramatsu Cc: Ingo Molnar Cc: Masami Hiramatsu Cc: Peter Zijlstra Cc: linux-kernel LKML-Reference: <1301041668.14111.52.camel@minggr.sh.intel.com> Signed-off-by: Lin Ming Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/probe-finder.c | 72 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 72 insertions(+) (limited to 'tools/perf/util/probe-finder.c') diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c index 194f9e2a3285..ff416b85f7e8 100644 --- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -1435,6 +1435,38 @@ static int find_probe_point_by_func(struct probe_finder *pf) return _param.retval; } +struct pubname_callback_param { + char *function; + char *file; + Dwarf_Die *cu_die; + Dwarf_Die *sp_die; + int found; +}; + +static int pubname_search_cb(Dwarf *dbg, Dwarf_Global *gl, void *data) +{ + struct pubname_callback_param *param = data; + + if (dwarf_offdie(dbg, gl->die_offset, param->sp_die)) { + if (dwarf_tag(param->sp_die) != DW_TAG_subprogram) + return DWARF_CB_OK; + + if (die_compare_name(param->sp_die, param->function)) { + if (!dwarf_offdie(dbg, gl->cu_offset, param->cu_die)) + return DWARF_CB_OK; + + if (param->file && + strtailcmp(param->file, dwarf_decl_file(param->sp_die))) + return DWARF_CB_OK; + + param->found = 1; + return DWARF_CB_ABORT; + } + } + + return DWARF_CB_OK; +} + /* Find probe points from debuginfo */ static int find_probes(int fd, struct probe_finder *pf) { @@ -1461,6 +1493,27 @@ static int find_probes(int fd, struct probe_finder *pf) off = 0; line_list__init(&pf->lcache); + + /* Fastpath: lookup by function name from .debug_pubnames section */ + if (pp->function) { + struct pubname_callback_param pubname_param = { + .function = pp->function, + .file = pp->file, + .cu_die = &pf->cu_die, + .sp_die = &pf->sp_die, + }; + struct dwarf_callback_param probe_param = { + .data = pf, + }; + + dwarf_getpubnames(dbg, pubname_search_cb, &pubname_param, 0); + if (pubname_param.found) { + ret = probe_point_search_cb(&pf->sp_die, &probe_param); + if (ret) + goto found; + } + } + /* Loop on CUs (Compilation Unit) */ while (!dwarf_nextcu(dbg, off, &noff, &cuhl, NULL, NULL, NULL)) { /* Get the DIE(Debugging Information Entry) of this CU */ @@ -1488,6 +1541,8 @@ static int find_probes(int fd, struct probe_finder *pf) } off = noff; } + +found: line_list__free(&pf->lcache); if (dwfl) dwfl_end(dwfl); @@ -1895,6 +1950,22 @@ int find_line_range(int fd, struct line_range *lr) return -EBADF; } + /* Fastpath: lookup by function name from .debug_pubnames section */ + if (lr->function) { + struct pubname_callback_param pubname_param = { + .function = lr->function, .file = lr->file, + .cu_die = &lf.cu_die, .sp_die = &lf.sp_die, .found = 0}; + struct dwarf_callback_param line_range_param = { + .data = (void *)&lf, .retval = 0}; + + dwarf_getpubnames(dbg, pubname_search_cb, &pubname_param, 0); + if (pubname_param.found) { + line_range_search_cb(&lf.sp_die, &line_range_param); + if (lf.found) + goto found; + } + } + /* Loop on CUs (Compilation Unit) */ while (!lf.found && ret >= 0) { if (dwarf_nextcu(dbg, off, &noff, &cuhl, NULL, NULL, NULL) != 0) @@ -1923,6 +1994,7 @@ int find_line_range(int fd, struct line_range *lr) off = noff; } +found: /* Store comp_dir */ if (lf.found) { comp_dir = cu_get_comp_dir(&lf.cu_die); -- cgit v1.2.1