lkml.org 
[lkml]   [2006]   [Mar]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Fix unlock_buffer() to work the same way as bit_unlock()
Chen, Kenneth W wrote:
> Nick Piggin wrote on Tuesday, March 28, 2006 12:11 AM
>
>>Also, I think there is still the issue of ia64 not having the
>>correct memory consistency semantics. To start with, all the bitops
>>and atomic ops which both modify their operand and return a value
>>should be full memory barriers before and after the operation,
>>according to Documentation/atomic_ops.txt.
>
> I suppose the usage of atomic ops is abused, it is used in both lock
> and unlock path. And it naturally suck because it now requires full
> memory barrier. A better way is to define 3 variants: one for lock
> path, one for unlock path, and one with full memory fence.

I agree. As I wrote a few days ago:

Why not to use separate bit operations for different purposes?

- e.g. "test_and_set_bit_N_acquire()" for lock acquisition
- "test_and_set_bit()", "clear_bit()" as they are today
- "release_N_clear_bit()"...

Thanks,

Zoltan

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-03-28 23:44    [W:0.158 / U:0.292 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site