Re: [patch 4/4] ipc: sem optimise simple operations

Zach Brown
2009-08-11T18:25:27Z

Manfred Spraul wrote:
> On 08/11/2009 01:09 PM, npiggin@suse.de wrote:
>> Index: linux-2.6/include/linux/sem.h
>> ===================================================================
>> --- linux-2.6.orig/include/linux/sem.h
>> +++ linux-2.6/include/linux/sem.h
>> @@ -86,6 +86,8 @@ struct task_struct;
>> struct sem {
>> int semval; /* current value */
>> int sempid; /* pid of last operation */
>> + struct list_head negv_pending;
>> + struct list_head zero_pending;
>> };
>>
> struct sem is increased from 8 to 24 bytes.

And larger still with 64bit pointers.

If it's a problem, this can be scaled back. You can have pointers to
lists and you can have fewer lists.

Hopefully it won't be a problem, though. We can close our eyes and
pretend that the size of the semaphore sets scale with the size of the
system and that it's such a relatively small consumer of memory that no
one will notice :).

- z