From 0f5486b5c71a831a713ce356d8d06822e3c7c379 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Thu, 4 Jun 2009 20:48:04 +0200 Subject: [PATCH] perf_counter: Sleep before refresh using poll in perf top perf top is refreshed every delay_secs the thread runs in such loop: while (sleep(delay_secs)) { print_sym_table(); } At the end of print_sym_table(), poll is used without sleep delay to check if we have something from stdin. It means that this check is done only every delay_secs, which can be higher that 2 secs if the user defined a custom refresh rate. We can drop sleep() here and directly use poll to wait between refresh periods, so that the reaction after the user stops perf top after typing "Enter" is immediate and doesn't suffer from the delay_secs latency. Nb: poll doesn't add any overhead that can parasite perf top measures since it sleeps the entire timeout here. Signed-off-by: Frederic Weisbecker Cc: Peter Zijlstra Cc: Mike Galbraith Cc: Paul Mackerras Cc: Corey Ashford Cc: Marcelo Tosatti Cc: Arnaldo Carvalho de Melo Cc: Frederic Weisbecker LKML-Reference: <1244141284-7507-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar --- Documentation/perf_counter/builtin-top.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-) diff --git a/Documentation/perf_counter/builtin-top.c b/Documentation/perf_counter/builtin-top.c index 31c00ba99b14..28cbde4b6e83 100644 --- a/Documentation/perf_counter/builtin-top.c +++ b/Documentation/perf_counter/builtin-top.c @@ -204,7 +204,7 @@ static void print_sym_table(void) list_remove_active_sym(syme); } - write(1, CONSOLE_CLEAR, strlen(CONSOLE_CLEAR)); + puts(CONSOLE_CLEAR); printf( "------------------------------------------------------------------------------\n"); @@ -278,23 +278,21 @@ static void print_sym_table(void) color_fprintf(stdout, color, "%4.1f%%", pcnt); printf(" - %016llx : %s\n", sym->start, sym->name); } - - { - struct pollfd stdin_poll = { .fd = 0, .events = POLLIN }; - - if (poll(&stdin_poll, 1, 0) == 1) { - printf("key pressed - exiting.\n"); - exit(0); - } - } } static void *display_thread(void *arg) { + struct pollfd stdin_poll = { .fd = 0, .events = POLLIN }; + int delay_msecs = delay_secs * 1000; + printf("PerfTop refresh period: %d seconds\n", delay_secs); - while (!sleep(delay_secs)) + do { print_sym_table(); + } while (!poll(&stdin_poll, 1, delay_msecs) == 1); + + printf("key pressed - exiting.\n"); + exit(0); return NULL; } -- 2.20.1