Include lkml in the CC: this time... *sigh*
---8<---

This series makes the sysv semaphore code more scalable,
by reducing the time the semaphore lock is held, and making
the locking more scalable for semaphore arrays with multiple
semaphores.

The first four patches were written by Davidlohr Buesso, and
reduce the hold time of the semaphore lock.

The last three patches change the sysv semaphore code locking
to be more fine grained, providing a performance boost when
multiple semaphores in a semaphore array are being manipulated
simultaneously.

On a 24 CPU system, performance numbers with the semop-multi
test with N threads and N semaphores, look like this:

        vanilla         Davidlohr's     Davidlohr's +   Davidlohr's +
threads                 patches         rwlock patches  v3 patches
10      610652          726325          1783589         2142206
20      341570          365699          1520453         1977878
30      288102          307037          1498167         2037995
40      290714          305955          1612665         2256484
50      288620          312890          1733453         2650292
60      289987          306043          1649360         2388008
70      291298          306347          1723167         2717486
80      290948          305662          1729545         2763582
90      290996          306680          1736021         2757524
100     292243          306700          1773700         3059159

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