On Sun, Oct 20, 2019 at 10:51:56AM -0700, Andi Kleen wrote: SNIP
> @@ -92,8 +93,12 @@ static int pmu_format(const char *name, struct list_head > *format) > snprintf(path, PATH_MAX, > "%s" EVENT_SOURCE_DEVICE_PATH "%s/format", sysfs, name); > > - if (stat(path, &st) < 0) > + if (lookup_fncache(path, &res) && !res) > + return 0; > + > + if (!res && access(path, R_OK) < 0) > return 0; /* no error if format does not exist */ > + update_fncache(path, true); > > if (perf_pmu__format_parse(path, format)) > return -1; > @@ -470,9 +475,9 @@ static int pmu_aliases_parse(char *dir, struct list_head > *head) > */ > static int pmu_aliases(const char *name, struct list_head *head) > { > - struct stat st; > char path[PATH_MAX]; > const char *sysfs = sysfs__mountpoint(); > + bool res = false; > > if (!sysfs) > return -1; > @@ -480,8 +485,11 @@ static int pmu_aliases(const char *name, struct > list_head *head) > snprintf(path, PATH_MAX, > "%s/bus/event_source/devices/%s/events", sysfs, name); > > - if (stat(path, &st) < 0) > - return 0; /* no error if 'events' does not exist */ > + if (lookup_fncache(path, &res) && !res) > + return 0; > + if (!res && access(path, R_OK) < 0) > + return 0; > + update_fncache(path, true); I was thinking that maybe you dont need to have the fncache::res, but then I realized we have 2 kind of information in here: - we processed this file - is present file present so I think you should update the result on each update_fncache call, not only when it's succesful also, could you please make single function API for this? sonething like: is_the_file_there(path) that would encapsulate those calls thanks, jirka