On 04/19/2018 01:38 PM, Randy Dunlap wrote: > On 04/19/18 10:09, Waiman Long wrote: >> It was found that reading /proc/stat could be time consuming on >> systems with a lot of irqs. For example, reading /proc/stat in a >> certain 2-socket Skylake server took about 4.6ms because it had over >> 5k irqs. In that particular case, the majority of the CPU cycles for >> reading /proc/stat was spent in the kstat_irqs() function. Therefore, >> application performance can be impacted if the application reads >> /proc/stat rather frequently. >> >> The "intr" line within /proc/stat contains a sum total of all the irqs >> that have happened followed by a list of irq counts for each individual >> irq number. In many cases, the first number is good enough. The >> individual irq counts may not provide that much more information. >> >> In order to avoid this kind of performance issue, all these individual >> irq counts are now separated into a new /proc/stat_irqs file. The >> sum total irq count will stay in /proc/stat and be duplicated in >> /proc/stat_irqs. Applications that need to look up individual irq counts >> will now have to look into /proc/stat_irqs instead of /proc/stat. >> >> Signed-off-by: Waiman Long <long...@redhat.com> >> --- >> fs/proc/stat.c | 48 +++++++++++++++++++++++++++++++++++++++++------- >> 1 file changed, 41 insertions(+), 7 deletions(-) > Also please update Documentation/filesystems/proc.txt. > > thanks,
Right. I forgot to do that. Will send out v2 to fix that. -Longman