Re: [Bug #11308] tbench regression on each kernel release from 2.6.22-> 2.6.28

[Eric Dumazet]

Ingo Molnar a écrit :
> * Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> > hmmm... Well we are almost there.
> >
> > 2.6.22:
> >
> > Throughput 2526.15 MB/sec 8 procs
> >
> > 2.6.28-rc5:
> >
> > Throughput 2486.2 MB/sec 8 procs
> >
> > 8p Dell 1950 and the number of processors specified on the tbench 
> > command line.
>
> And with net-next we might even be able to get past that magic limit? 
> net-next is linus-latest plus the latest and greatest networking bits:
>
>  $ cat .git/config
>
>  [remote "net-next"]
> 	url = git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6.git
> 	fetch = +refs/heads/*:refs/remotes/net-next/*
>
> ... so might be worth a test. Just to satisfy our curiosity and to 
> possibly close the entry :-)

Well, bits in net-next are new stuff for 2.6.29, not really regression fixes,
but yes, they should give nice tbench speedups.


Now, I wish sockets and pipes not going through dcache, not tbench affair
of course but real workloads...

running 8 processes on a 8 way machine doing a 

for (;;)
	close(socket(AF_INET, SOCK_STREAM, 0));

is slow as hell, we hit so many contended cache lines ...

ticket spin locks are slower in this case (dcache_lock for example
is taken twice when we allocate a socket(), once in d_alloc(), another one
in d_instantiate())


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