Re: regression with poll(2)

[Eric Dumazet <eric.dumazet@gmail.com>]

On Mon, 2012-08-20 at 16:20 -0700, Andrew Morton wrote:
> On Mon, 20 Aug 2012 11:30:59 +0200
> Eric Dumazet <eric.dumazet@gmail.com> wrote:
> 
> > On Mon, 2012-08-20 at 10:04 +0100, Mel Gorman wrote:
> > 
> > > 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.