Driver patch to look at...

[Randall Stewart]

Ok

Here it is one last time (I hope) with the updates ;-)

R

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On Feb 5, 2013, at 2:11 PM, John Baldwin wrote:

> On Tuesday, February 05, 2013 2:08:15 pm Randall Stewart wrote:
>> Hmm
>> 
>> wait, I could probably do the compare to whats in the ring buffer ;-D
> 
> I wouldn't bother.  The compare and branch is probably more expensive than
> the store.
> 
>> R
>> On Feb 5, 2013, at 2:04 PM, Randall Stewart wrote:
>> 
>>> Hmm
>>> 
>>> That would trade off a stack pointer + a compare
>>> vs always doing the move.
>>> 
>>> Thats fine until I have to add the _mc() version, then the put
>>> back would be an atomic, and most of the time the return from
>>> this is probably not changed…
>>> 
>>> I really would prefer not to since the compare and maybe store vs
>>> the always store.. though the same now, would be far more expensive
>>> in the _mc version.. if we do a _mc version of course ;-)
>>> 
>>> But I am willing to do whatever .. since this really needs to be fixed.
>>> 
>>> R
>>> On Feb 5, 2013, at 1:52 PM, John Baldwin wrote:
>>> 
>>>> On Tuesday, February 05, 2013 12:44:01 pm Randall Stewart wrote:
>>>>> Actually, no it is used.
>>>>> 
>>>>> If you look in if_var.h int he drbr_putback() function, it does
>>>>> a buf_ring_swap when the old mbuf pointer does not equal the
>>>>> new mbuf pointer. This *does* happen, I crashed at least once
>>>>> yesterday when the igb driver did something to free the original
>>>>> mbuf and return a new mbuf with the data (prepend or some such).
>>>>> 
>>>>> I also have found several issues that I have fixed this morning.. its been
>>>>> crash city on my test beds..
>>>>> 
>>>>> Here is the latest patch with all fixes and suggested changes from emaste 
>>>> (thanks Ed)
>>>> 
>>>> Actually, one more suggestion then (since you have to keep putback).  It
>>>> would be nice to not have to require 'snext' in all the callers.  How
>>>> about replace buf_ring_swap() with a buf_ring_putback_sc() that accepts the
>>>> mbuf and just stores it at the head unconditionally and have drbr_putback()
>>>> use that?
>>>> 
>>>> -- 
>>>> John Baldwin
>>>> _______________________________________________
>>>> freebsd-net at freebsd.org mailing list
>>>> http://lists.freebsd.org/mailman/listinfo/freebsd-net
>>>> To unsubscribe, send any mail to "freebsd-net-unsubscribe at freebsd.org"
>>>> 
>>> 
>>> ------------------------------
>>> Randall Stewart
>>> 803-317-4952 (cell)
>>> 
>>> _______________________________________________
>>> freebsd-net at freebsd.org mailing list
>>> http://lists.freebsd.org/mailman/listinfo/freebsd-net
>>> To unsubscribe, send any mail to "freebsd-net-unsubscribe at freebsd.org"
>>> 
>> 
>> ------------------------------
>> Randall Stewart
>> 803-317-4952 (cell)
>> 
>> 
> 
> -- 
> John Baldwin
> _______________________________________________
> freebsd-net at freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-net
> To unsubscribe, send any mail to "freebsd-net-unsubscribe at freebsd.org"
> 

------------------------------
Randall Stewart
803-317-4952 (cell)