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Date:      Fri, 6 May 2005 16:09:52 -0700
From:      Kris Kennaway <kris@obsecurity.org>
To:        ticso@cicely.de
Cc:        Kris Kennaway <kris@obsecurity.org>
Subject:   Re: Benchmarking mpsafevfs with parallel tarball extraction
Message-ID:  <20050506230952.GB35398@xor.obsecurity.org>
In-Reply-To: <20050506225926.GB75629@cicely12.cicely.de>
References:  <20050506183529.GA46411@xor.obsecurity.org> <20050506184852.GA62656@xor.obsecurity.org> <20050506200635.GB79102@xor.obsecurity.org> <20050506225926.GB75629@cicely12.cicely.de>

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On Sat, May 07, 2005 at 12:59:27AM +0200, Bernd Walter wrote:
> On Fri, May 06, 2005 at 01:06:35PM -0700, Kris Kennaway wrote:
> > On Fri, May 06, 2005 at 11:48:52AM -0700, Kris Kennaway wrote:
> > > On Fri, May 06, 2005 at 11:35:29AM -0700, Kris Kennaway wrote:
> > >=20
> > > > I might be bumping into the bandwidth of md here - when I ran less
> > > > rigorous tests with lower concurrency of extractions I seemed to be
> > > > getting marginally better performance (about an effective concurren=
cy
> > > > of 2.2 for both 3 and 10 simultaneous extractions - so at least it
> > > > doesn't seem to degrade badly).  Or this might be reflecting VFS lo=
ck
> > > > contention (which there is certainly a lot of, according to mutex
> > > > profiling traces).
> > >=20
> > > I suspect that I am hitting the md bandwidth:
> > >=20
> > > # dd if=3D/dev/zero of=3D/dev/md0 bs=3D1024k count=3D500
> > > 500+0 records in
> > > 500+0 records out
> > > 524288000 bytes transferred in 9.501760 secs (55177988 bytes/sec)
>=20
> Wasn't md's blocksize =3D systems's pagesize, IIRC 8k on sparc.
> I'm surprised that 1k even works.

1M block size, not 1K :)

Kris

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