Re: regression with poll(2)

On Mon, 2012-08-20 at 16:20 -0700, Andrew Morton wrote:

On Mon, 20 Aug 2012 11:30:59 +0200
Eric Dumazet [off-list ref] wrote:

quoted

On Mon, 2012-08-20 at 10:04 +0100, Mel Gorman wrote:

quoted

Can the following patch be tested please? It is reported to fix an fio
regression that may be similar to what you are experiencing but has not
been picked up yet.

-

This seems to help here.

Boot your machine with "mem=768M" or a bit less depending on your setup,
and try a netperf.

-> before patch :

# netperf
MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to
localhost.localdomain () port 0 AF_INET
Recv   Send    Send                          
Socket Socket  Message  Elapsed              
Size   Size    Size     Time     Throughput  
bytes  bytes   bytes    secs.    10^6bits/sec  

 87380  16384  16384    14.00       6.05   

-> after patch :

Recv   Send    Send                          
Socket Socket  Message  Elapsed              
Size   Size    Size     Time     Throughput  
bytes  bytes   bytes    secs.    10^6bits/sec  

 87380  16384  16384    10.00    18509.73   

"seem to help"?  Was previous performance fully restored?

I did some tests this morning on my HP Z600, and got same numbers than
3.5.0

Of course, its a bit difficult to say, because there is no
CONFIG_PFMEMALLOC to test real impact.