Re: [Powertop] [PATCH] cpufreq: only try to open files under cpuX

[Sergey Senozhatsky <sergey.senozhatsky at gmail.com>]

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On (12/13/12 09:43), Jaroslav Skarvada wrote:
> There are called many useless 'open' syscalls that always fail, like:
>   open("/sys/devices/system/cpu/uevent/cpufreq/scaling_governor", O_RDONLY) = -1 ENOTDIR (Not a directory)
> This patch filters them to 'likely' patterns, like e.g.:
> /sys/devices/system/cpu/cpuX/cpufreq/scaling_governor, where X is string
> starting with digit. For match cases it will add only small overhead.
> 
> Originally reported as:
> https://bugzilla.redhat.com/show_bug.cgi?id=886185
> 
> Signed-off-by: Jaroslav ??karvada <jskarvad(a)redhat.com>
> ---
>  src/devices/alsa.cpp       |  2 +-
>  src/devices/backlight.cpp  |  2 ++
>  src/devlist.cpp            |  3 ++-
>  src/tuning/cpufreq.cpp     | 11 ++++++-----
>  src/tuning/tuningsysfs.cpp |  5 +----
>  5 files changed, 12 insertions(+), 11 deletions(-)
>

looks good to me, thanks.

	-ss

 
> diff --git a/src/devices/alsa.cpp b/src/devices/alsa.cpp
> index 4f5d3f9..33a52f5 100644
> --- a/src/devices/alsa.cpp
> +++ b/src/devices/alsa.cpp
> @@ -167,7 +167,7 @@ void create_all_alsa(void)
>  		entry = readdir(dir);
>  		if (!entry)
>  			break;
> -		if (entry->d_name[0] == '.')
> +		if (strncmp(entry->d_name, "hwC", 3) != 0)
>  			continue;
>  		sprintf(filename, "/sys/class/sound/card0/%s/power_on_acct", entry->d_name);
>  
> diff --git a/src/devices/backlight.cpp b/src/devices/backlight.cpp
> index b8c9147..03aa5bc 100644
> --- a/src/devices/backlight.cpp
> +++ b/src/devices/backlight.cpp
> @@ -90,6 +90,8 @@ static int dpms_screen_on(void)
>  		if (!entry)
>  			break;
>  
> +		if (strncmp(entry->d_name, "card", 4) != 0)
> +			continue;
>  		sprintf(filename, "/sys/class/drm/card0/%s/enabled", entry->d_name);
>  		file.open(filename, ios::in);
>  		if (!file)
> diff --git a/src/devlist.cpp b/src/devlist.cpp
> index de5abff..633a568 100644
> --- a/src/devlist.cpp
> +++ b/src/devlist.cpp
> @@ -37,6 +37,7 @@
>  #include <sys/types.h>
>  #include <dirent.h>
>  #include <string.h>
> +#include <ctype.h>
>  
>  using namespace std;
>  
> @@ -117,7 +118,7 @@ void collect_open_devices(void)
>  			entry2 = readdir(dir2);
>  			if (!entry2)
>  				break;
> -			if (entry2->d_name[0] == '.')
> +			if (!isdigit(entry2->d_name[0]))
>  				continue;
>  			sprintf(filename, "/proc/%s/fd/%s", entry->d_name, entry2->d_name);
>  			memset(link, 0, 4096);
> diff --git a/src/tuning/cpufreq.cpp b/src/tuning/cpufreq.cpp
> index df245ad..e870559 100644
> --- a/src/tuning/cpufreq.cpp
> +++ b/src/tuning/cpufreq.cpp
> @@ -36,6 +36,7 @@
>  #include <dirent.h>
>  #include <errno.h>
>  #include <sys/stat.h>
> +#include <ctype.h>
>  
>  #include "../lib.h"
>  #include "cpufreq.h"
> @@ -72,7 +73,7 @@ int cpufreq_tunable::good_bad(void)
>  		return ret;
>  
>  	while ((dirent = readdir(dir))) {
> -		if (dirent->d_name[0]=='.')
> +		if (strncmp(dirent->d_name, "cpu", 3) != 0 || !isdigit(dirent->d_name[3]))
>  			continue;
>  		sprintf(filename, "/sys/devices/system/cpu/%s/cpufreq/scaling_governor", dirent->d_name);
>  		file = fopen(filename, "r");
> @@ -123,7 +124,7 @@ void cpufreq_tunable::toggle(void)
>  			return;
>  
>  		while ((dirent = readdir(dir))) {
> -			if (dirent->d_name[0]=='.')
> +			if (strncmp(dirent->d_name, "cpu", 3) != 0 || !isdigit(dirent->d_name[3]))
>  				continue;
>  			sprintf(filename, "/sys/devices/system/cpu/%s/cpufreq/scaling_governor", dirent->d_name);
>  			file = fopen(filename, "w");
> @@ -141,7 +142,7 @@ void cpufreq_tunable::toggle(void)
>  		return;
>  
>  	while ((dirent = readdir(dir))) {
> -		if (dirent->d_name[0]=='.')
> +		if (strncmp(dirent->d_name, "cpu", 3) != 0 || !isdigit(dirent->d_name[3]))
>  			continue;
>  		sprintf(filename, "/sys/devices/system/cpu/%s/cpufreq/scaling_governor", dirent->d_name);
>  		file = fopen(filename, "w");
> @@ -171,7 +172,7 @@ const char *cpufreq_tunable::toggle_script(void) {
>  			return NULL;
>  
>  		while ((dirent = readdir(dir))) {
> -			if (dirent->d_name[0]=='.')
> +			if (strncmp(dirent->d_name, "cpu", 3) != 0 || !isdigit(dirent->d_name[3]))
>  				continue;
>  			sprintf(filename, "/sys/devices/system/cpu/%s/cpufreq/scaling_governor", dirent->d_name);
>  			if (stat(filename, &statbuf) == -1)
> @@ -189,7 +190,7 @@ const char *cpufreq_tunable::toggle_script(void) {
>  		return NULL;
>  
>  	while ((dirent = readdir(dir))) {
> -		if (dirent->d_name[0]=='.')
> +		if (strncmp(dirent->d_name, "cpu", 3) != 0 || !isdigit(dirent->d_name[3]))
>  			continue;
>  		sprintf(filename, "/sys/devices/system/cpu/%s/cpufreq/scaling_governor", dirent->d_name);
>  		if (stat(filename, &statbuf) == -1)
> diff --git a/src/tuning/tuningsysfs.cpp b/src/tuning/tuningsysfs.cpp
> index 33d3786..ec1ca6b 100644
> --- a/src/tuning/tuningsysfs.cpp
> +++ b/src/tuning/tuningsysfs.cpp
> @@ -131,10 +131,7 @@ void add_sata_tunables(void)
>  		if (!entry)
>  			break;
>  
> -                if (strcmp(entry->d_name, ".") == 0)
> -                        continue;
> -
> -		if (strcmp(entry->d_name, "..") == 0)
> +		if (entry->d_name[0] == '.')
>  			continue;
>  
>  		sprintf(filename, "/sys/class/scsi_host/%s/link_power_management_policy", entry->d_name);
> -- 
> 1.7.11.7
> 

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