On 02/28/2013 03:26 PM, Linus Torvalds wrote: > On Thu, Feb 28, 2013 at 10:22 AM, Linus Torvalds > wrote: >> >> I'm sure there are other things we could do to improve ipc lock times >> even if we don't actually split the lock, but the security one might >> be a good first step. > > Btw, if somebody has a benchmark for threads using multiple ipc > semaphores (from the same semget() allocation) concurrently, and we > could have a simple way to see the contention without having to run > some big DB thing, that would also be nice. Maybe there is something > out there already? Google didn't find any, and the normal benchmarks > I'm aware of all just do one single (private) ipc semaphore per > process. > > Nothing gets some people going like just having a nice benchmark to > show the effect. I have modified one of the semop tests to use multiple semaphores. To run the test, specify the number of threads. If you want the number of semaphores to be different from the number of threads, specify a second commandline argument. $ ./semop-multi usage: ./semop-multi [nsems]