sem.c multithreading

Christoph Rohland (hans-christoph.rohland@sap.com)
01 Nov 1999 14:00:35 +0100


Hi Manfred,

I just got the 2.3.25 prepatch with your semaphore changes. That's a
great enhancement, but wouldn't it be better to include the per
semaphore lock into the semaphore structure instead of preallocating
it in the administration array?

I am just working on making the shm and sem limits sysctl'able. Here I
run into many inherent problems with these fixed size arrays:

You lock a lot of memory (and your patch doubles this locked memory)
If you kmalloc this you run into problems with high limits...

So I would suggest to invent a new structure

struct semid_kernel {
spinlock_t lock;
struct semid_ds u;
}

like we do for shm.

What do you think?

Christoph

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