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, -- ~Randy