Messages in this thread | | | Date | Fri, 2 Jul 2010 13:21:41 +0200 | From | Steffen Klassert <> | Subject | Re: [PATCH 2/2] pcrypt: sysfs interface |
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On Fri, Jul 02, 2010 at 02:20:15PM +0400, Dan Kruchinin wrote: > > > > Yes, I thought about something like this. You can still take the sum > > over the percpu objects when you output the statistics. > > But summation can not be clear without some kind of lock because > while we're summing another CPU can increase or decrease its percpu statistic > counters. Then each statistic percpu counter must be modified under lock, right? >
Yes, the counters must accessed under lock. In the fastpath functions you hold the appropriate lock anyway. Modifying a local percpu value should not be too painfull there.
The expensive thing is to access the percpu statistics, but this happens on demand and is probaply a rare event.
Steffen
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