From 6b5107d91827962808441db6b98e478aa9e67bdb Mon Sep 17 00:00:00 2001 From: Tvrtko Ursulin Date: Mon, 6 Jun 2022 14:04:46 +0100 Subject: intel-gpu-top: Optimise the scanning loop a bit Opendir(3) and fdopendir(3) are quite expensive system calls when ran in a loop which iterates all processes in a system times all open files in each. Replace some of them (easy ones) with simpler open(2)/read(2) combo to avoid hammering on the malloc/free. This brings the default CPU usage of the tool on my desktop from ~3% to ~2%. Signed-off-by: Tvrtko Ursulin Reviewed-by: Umesh Nerlige Ramappa --- tools/intel_gpu_top.c | 66 ++++++++++++++++++++++----------------------------- 1 file changed, 29 insertions(+), 37 deletions(-) (limited to 'tools') diff --git a/tools/intel_gpu_top.c b/tools/intel_gpu_top.c index 997aff58..6de8a164 100644 --- a/tools/intel_gpu_top.c +++ b/tools/intel_gpu_top.c @@ -1022,12 +1022,12 @@ static void free_clients(struct clients *clients) free(clients); } -static bool is_drm_fd(DIR *fd_dir, const char *name) +static bool is_drm_fd(int fd_dir, const char *name) { struct stat stat; int ret; - ret = fstatat(dirfd(fd_dir), name, &stat, 0); + ret = fstatat(fd_dir, name, &stat, 0); return ret == 0 && (stat.st_mode & S_IFMT) == S_IFCHR && @@ -1054,12 +1054,12 @@ static bool get_task_name(const char *buffer, char *out, unsigned long sz) return true; } -static DIR *opendirat(DIR *at, const char *name) +static DIR *opendirat(int at, const char *name) { DIR *dir; int fd; - fd = openat(dirfd(at), name, O_DIRECTORY); + fd = openat(at, name, O_DIRECTORY); if (fd < 0) return NULL; @@ -1070,37 +1070,27 @@ static DIR *opendirat(DIR *at, const char *name) return dir; } -static FILE *fropenat(DIR *at, const char *name) +static size_t readat2buf(int at, const char *name, char *buf, const size_t sz) { - FILE *f; + ssize_t count; int fd; - fd = openat(dirfd(at), name, O_RDONLY); - if (fd < 0) - return NULL; + fd = openat(at, name, O_RDONLY); + if (fd <= 0) + return 0; - f = fdopen(fd, "r"); - if (!f) - close(fd); + count = read(fd, buf, sz - 1); + close(fd); - return f; -} + if (count > 0) { + buf[count] = 0; -static size_t freadat2buf(char *buf, const size_t sz, DIR *at, const char *name) -{ - size_t count; - FILE *f; + return count; + } else { + buf[0] = 0; - f = fropenat(at, name); - if (!f) return 0; - - buf[sz - 1] = 0; - count = fread(buf, 1, sz, f); - buf[count - 1] = 0; - fclose(f); - - return count; + } } static struct clients *scan_clients(struct clients *clients, bool display) @@ -1126,10 +1116,11 @@ static struct clients *scan_clients(struct clients *clients, bool display) return clients; while ((proc_dent = readdir(proc_dir)) != NULL) { - DIR *pid_dir = NULL, *fd_dir = NULL, *fdinfo_dir = NULL; + int pid_dir = -1, fd_dir = -1; struct dirent *fdinfo_dent; char client_name[64] = { }; unsigned int client_pid; + DIR *fdinfo_dir = NULL; char buf[4096]; size_t count; @@ -1138,11 +1129,12 @@ static struct clients *scan_clients(struct clients *clients, bool display) if (!isdigit(proc_dent->d_name[0])) continue; - pid_dir = opendirat(proc_dir, proc_dent->d_name); - if (!pid_dir) + pid_dir = openat(dirfd(proc_dir), proc_dent->d_name, + O_DIRECTORY | O_RDONLY); + if (pid_dir < 0) continue; - count = freadat2buf(buf, sizeof(buf), pid_dir, "stat"); + count = readat2buf(pid_dir, "stat", buf, sizeof(buf)); if (!count) goto next; @@ -1153,8 +1145,8 @@ static struct clients *scan_clients(struct clients *clients, bool display) if (!get_task_name(buf, client_name, sizeof(client_name))) goto next; - fd_dir = opendirat(pid_dir, "fd"); - if (!fd_dir) + fd_dir = openat(pid_dir, "fd", O_DIRECTORY | O_RDONLY); + if (fd_dir < 0) goto next; fdinfo_dir = opendirat(pid_dir, "fdinfo"); @@ -1196,10 +1188,10 @@ static struct clients *scan_clients(struct clients *clients, bool display) next: if (fdinfo_dir) closedir(fdinfo_dir); - if (fd_dir) - closedir(fd_dir); - if (pid_dir) - closedir(pid_dir); + if (fd_dir >= 0) + close(fd_dir); + if (pid_dir >= 0) + close(pid_dir); } closedir(proc_dir); -- cgit v1.2.3