Attachment 203251 Details for Bug 301821 – Patch to avoid unnecessary lookups and small optimizations

[patch] Patch to avoid unnecessary lookups and small optimizations

d-irqbalance-cputree (text/plain), 3.82 KB, created by Ulrich Drepper on 2007-09-22 22:20:42 UTC

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Creator: Ulrich Drepper

Created: 2007-09-22 22:20:42 UTC

Size: 3.82 KB

patch

obsolete

>--- irqbalance-0.55/cputree.c.old	2006-12-10 12:04:59.000000000 -0800
>+++ irqbalance-0.55/cputree.c	2007-09-22 15:06:01.000000000 -0700
>@@ -26,6 +26,8 @@
> 
> #define _GNU_SOURCE
> 
>+#include <ctype.h>
>+#include <fcntl.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <unistd.h>
>@@ -131,34 +133,30 @@
> }
> 
> 
>-static void do_one_cpu(char *path)
>+static void do_one_cpu(int dfd, char *d_name)
> {
> 	struct cpu_core *cpu;
> 	FILE *file;
> 	char new_path[PATH_MAX];
> 
> 	/* skip offline cpus */
>-	snprintf(new_path, PATH_MAX, "%s/online", path);
>-	file = fopen(new_path, "r");
>-	if (file) {
>-		char *line = NULL;
>-		size_t size = 0;
>-		if (getline(&line, &size, file)==0)
>+	snprintf(new_path, PATH_MAX, "%s/online", d_name);
>+	int fd = openat(dfd, new_path, O_RDONLY);
>+	if (fd != -1) {
>+		char buf[1];
>+		ssize_t n = read(fd, buf, sizeof(buf));
>+		close(fd);
>+		if (n != sizeof(buf))
> 			return;
>-		fclose(file);
>-		if (line && line[0]=='0') {
>-			free(line);
>+		if (buf[0] == '0')
> 			return;
>-		}
>-		free(line);
> 	}
> 
>-	cpu = malloc(sizeof(struct cpu_core));
>+	cpu = calloc(1, sizeof(struct cpu_core));
> 	if (!cpu)
> 		return;
>-	memset(cpu, 0, sizeof(struct cpu_core));
> 
>-	cpu->number = strtoul(&path[27], NULL, 10);
>+	cpu->number = strtoul(&d_name[3], NULL, 10);
> 	
> 	cpu_set(cpu->number, cpu->mask);
> 
>@@ -170,43 +168,45 @@
> 		return;
> 	}
> 
>+	char *line = NULL;
>+	size_t size = 0;
> 
> 	/* try to read the package mask; if it doesn't exist assume solitary */
>-	snprintf(new_path, PATH_MAX, "%s/topology/core_siblings", path);
>-	file = fopen(new_path, "r");
>+	snprintf(new_path, PATH_MAX, "%s/topology/core_siblings", d_name);
>+	fd = openat(dfd, new_path, O_RDONLY);
>+	file = fd == -1 ? NULL : fdopen(fd, "r");
> 	cpu_set(cpu->number, cpu->package_mask);
> 	if (file) {
>-		char *line = NULL;
>-		size_t size = 0;
> 		if (getline(&line, &size, file)) 
> 			cpumask_parse_user(line, strlen(line), cpu->package_mask);
> 		fclose(file);
>-		free(line);
>-	}
>+	} else if (fd != -1)
>+		close(fd);
> 
> 	/* try to read the cache mask; if it doesn't exist assume solitary */
> 	/* We want the deepest cache level available so try index1 first, then index2 */
> 	cpu_set(cpu->number, cpu->cache_mask);
>-	snprintf(new_path, PATH_MAX, "%s/cache/index1/shared_cpu_map", path);
>-	file = fopen(new_path, "r");
>+	snprintf(new_path, PATH_MAX, "%s/cache/index1/shared_cpu_map", d_name);
>+	fd = openat(dfd, new_path, O_RDONLY);
>+	file = fd == -1 ? NULL : fdopen(fd, "r");
> 	if (file) {
>-		char *line = NULL;
>-		size_t size = 0;
> 		if (getline(&line, &size, file)) 
> 			cpumask_parse_user(line, strlen(line), cpu->cache_mask);
> 		fclose(file);
>-		free(line);
>-	}
>-	snprintf(new_path, PATH_MAX, "%s/cache/index2/shared_cpu_map", path);
>-	file = fopen(new_path, "r");
>+	} else if (fd != -1)
>+		close(fd);
>+
>+	snprintf(new_path, PATH_MAX, "%s/cache/index2/shared_cpu_map", d_name);
>+	fd = openat(dfd, new_path, O_RDONLY);
>+	file = fd == -1 ? NULL : fdopen(fd, "r");
> 	if (file) {
>-		char *line = NULL;
>-		size_t size = 0;
> 		if (getline(&line, &size, file)) 
> 			cpumask_parse_user(line, strlen(line), cpu->cache_mask);
> 		fclose(file);
>-		free(line);
>-	}
>+	} else if (fd != -1)
>+		close(fd);
>+
>+	free(line);
> 
> 	/* 
> 	   blank out the banned cpus from the various masks so that interrupts
>@@ -311,18 +311,19 @@
> {
> 	DIR *dir;
> 	struct dirent *entry;
>+	int dfd;
> 
> 	cpus_complement(unbanned_cpus, banned_cpus);
> 
> 	dir = opendir("/sys/devices/system/cpu");
> 	if (!dir)
> 		return;
>+	dfd = dirfd(dir);
> 	do {
> 		entry = readdir(dir);
>-                if (entry && strlen(entry->d_name)>3 && strstr(entry->d_name,"cpu")) {
>-			char new_path[PATH_MAX];
>-			sprintf(new_path, "/sys/devices/system/cpu/%s", entry->d_name);
>-			do_one_cpu(new_path);
>+                if (entry && strlen(entry->d_name)>3 && memcmp(entry->d_name,"cpu",3) == 0
>+		    && isdigit(entry->d_name[3])) {
>+			do_one_cpu(dfd, entry->d_name);
> 		}
> 	} while (entry);
> 	closedir(dir);

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Attachments on bug 301821: 203251