lkml.org 
[lkml]   [2005]   [Feb]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] allow vma merging with mlock et. al.
Chris Wright wrote:
> * Chris Wright (chrisw@osdl.org) wrote:
>
>>* Darren Hart (dvhltc@us.ibm.com) wrote:
>>
>>>The were a couple long standing (since at least 2.4.21) superfluous
>>>variables and two unnecessary assignments in do_mlock(). The intent of
>>>the resulting code is also more obvious.
>>>
>>>Tested on a 4 way x86 box running a simple mlock test program. No
>>>problems detected.
>>
>>Did you test with multiple page ranges, and locking subsets of vmas?
>>Seems that splitting could cause a problem since you now sample vm_end
>>before and after fixup, where the vma could be changed in the middle.
>
>
> Actually I think it winds up being fine since we don't do merging with
> mlock. But why not? Patch below remedies that.

We don't merge, but we do split if necessary, so the temp variables are
still needed. As I understand it, the reason we don't merge is because
it is expected that a task will lock and unlock the same memory range
more than once and we don't want to waste our time merging and splitting
the VMAs.

Thanks,

--Darren
-
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: 2005-03-22 14:10    [W:0.174 / U:0.528 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site