Arjan van de Ven wrote:
On Tue, 2005-03-01 at 12:15 -0800, Greg KH wrote:Yes, that helps a lot. I had actually already implemented something like that :). But that's a different thing than avoiding the lock.
On Sat, Feb 26, 2005 at 04:23:04PM -0600, Corey Minyard wrote:
Add a routine to kref that allows the kref_put() routine to be unserialized even when the get routine attempts to kref_get() an object without first holding a valid reference to it. This is useful in situations where this happens multiple times without freeing the object, as it will avoid having to do a lock/semaphore except on the final kref_put().
This also adds some kref documentation to the Documentation
directory.
I like the first part of the documentation, that's nice.
But I don't like the new kref_get_with_check() function that you implemented. If you look in the -mm tree, kref_put() now returns if this was the last put on the reference count or not, to help with lists of objects with a kref in it.
Perhaps you can use that to implement what you need instead?
It's just that with the I2C stuff, you may be calling kref_put() 20-30 times for a single operation. That's a lot of lock/unlock operations. But it is wierd, so I understand. Thanks.
Just doing an atomic operation is not faster than doing a lock, an atomic operation, then an unlock? Am I missing something?
note that I'm not convinced the "lockless" implementation actually is
faster. It still uses an atomic variable, which is just as expensive as
taking a lock normally...
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