Re: vm-pageout-throttling.patch: hanging in throttle_vm_writeout/blk_congestion_wait

[Hans Reiser <reiser@namesys.com>]

Sami Farin wrote:

>On Mon, Nov 15, 2004 at 09:56:29PM +0000, Hugh Dickins wrote:
>  
>
>>On Mon, 15 Nov 2004, Sami Farin wrote:
>>    
>>
>>>this time I had some swapspace on /dev/loop1 (file-backed, reiserfs,
>>>loop-AES-2.2d)...  I think (!) it caused this deadlock.
>>>      
>>>
>>That's not at all surprising.  See the swap_extent work Andrew did
>>for 2.5 (in mm/swapfile.c), by which swap to a swapfile now avoids
>>the filesystem altogether (except while swapon prepares the map of
>>disk blocks).  By swapping to a loop device over a file, you're
>>sneaking past his work, and putting the filesystem back under swap.
>>    
>>

Does Andrew's approach prevent putting swap on a compressed file (useful 
for reiser4 once the compression plugin is stable, not reiserfs)? (And 
no, I don't have any idea what the performance effect of that would be 
before it is tried and benchmarked....)