----- Original Message ----
> From: Andrew Morton <[email protected]>
> To: Arjan van de Ven <[email protected]>
> Cc: Ingo Molnar <[email protected]>; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]
> Sent: Saturday, October 27, 2007 7:59:51 AM
> Subject: Re: 2.6.24-rc1: First impressions
>
> On Fri, 26 Oct 2007 22:46:57 -0700 Arjan van de
> Ven
>
wrote:
>
> > > > > dd1 - copy 16 GB from /dev/zero to local FS
> > > > > dd1-dir - same, but using O_DIRECT for output
> > > > > dd2/dd2-dir - copy 2x7.6 GB in parallel from /dev/zero to
> local
>
FS
> > > > > dd3/dd3-dir - copy 3x5.2 GB in parallel from /dev/zero lo
> local
>
FS
> > > > > net1 - copy 5.2 GB from NFS3 share to local FS
> > > > > mix3 - copy 3x5.2 GB from /dev/zero to local disk and two NFS3
> > > > > shares
> > > > >
> > > > > I did the numbers for 2.6.19.2, 2.6.22.6 and 2.6.24-rc1. All
> > > > > units are MB/sec.
> > > > >
> > > > > test 2.6.19.2 2.6.22.6 2.6.24.-rc1
> > > >
> >
>
----------------------------------------------------------------
> > > > > dd1 28 50 96
> > > > > dd1-dir 88 88 86
> > > > > dd2 2x16.5 2x11 2x44.5
> > > > > dd2-dir 2x44 2x44 2x43
> > > > > dd3 3x9.8 3x8.7 3x30
> > > > > dd3-dir 3x29.5 3x29.5 3x28.5
> > > > > net1 30-33 50-55 37-52
> > > > > mix3 17/32 25/50 96/35
> > > > > (disk/combined-network)
> > > >
> > > > wow, really nice results!
> > >
> > > Those changes seem suspiciously large to me. I wonder if
> there's
>
less
> > > physical IO happening during the timed run, and
> correspondingly
>
more
> > > afterwards.
> > >
> >
> > another option... this is ext2.. didn't the ext2 reservation
> stuff
>
get
> > merged into -rc1? for ext3 that gave a 4x or so speed boost (much
> > better sequential allocation pattern)
> >
>
> Yes, one would expect that to make a large difference in
> dd2/dd2-dir
>
and
> dd3/dd3-dir - but only on SMP. On UP there's not enough concurrency
> in the fs block allocator for any damage to occur.
>
Just for the record the test are done on SMP.
> Reservations won't affect dd1 though, and that went faster too.
>
This is the one result that surprised me most, as I did not really expect any big moves here. I am not complaining :-), but definitely it would be nice to understand the why.
Cheers
Martin
>
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