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Date:      Mon, 02 Feb 2009 10:16:30 +0100
From:      Ivan Voras <ivoras@freebsd.org>
To:        freebsd-geom@freebsd.org
Subject:   Re: Performance numbers?
Message-ID:  <gm6dlq$lcj$1@ger.gmane.org>
In-Reply-To: <9C533E30-BD08-4938-8D1A-5CE046FB6BF6@freebsd.org>
References:  <6612C205-C346-4493-9DA4-3B5A73E9A4F7@freebsd.org>	<glvp7l$6td$3@ger.gmane.org> <9C533E30-BD08-4938-8D1A-5CE046FB6BF6@freebsd.org>

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Eric Anderson wrote:
>=20
> On Jan 30, 2009, at 2:50 PM, Ivan Voras wrote:
>=20
>> Eric Anderson wrote:
>>> Hi GEOMers!
>>>
>>> Does anyone have any benchmarks or numbers relating to GEOM performan=
ce?
>>>
>>> I tried doing some on my own, but I didn't get very satisfactory
>>> results, so I'm curious what others have seen or used.
>>>
>>> My hardware is a Core 2 Quad, with 4GB of ram.
>>>
>>> First, I made an mdconfig'ed malloc backed 'disk' of 1.5GB.  Then, I
>>> tried running such tools as rawio, and diskinfo.  rawio fails with
>>> input/output errors, and diskinfo wants a larger device to give the f=
ull
>>> stats.  I ended up using purely dd since that worked.  Interestingly
>>> enough, dd'ing to the malloc device results in about 1000 operations =
per
>>> second, regardless of a blocksize of 512bytes or 1MB.
>>
>> It's a good idea for testing.
>>
>> 1000 ops/s looks suspiciously like HZ, though I don't know why HZ woul=
d
>> influence GEOM (AFAIK context switches between threads, including GEOM=

>> threads do not depend on it) - can you try ruling out HZ?
>=20
> Is there a way to pump the data through the GEOM layers without doing a=

> mdconfig'd disk?

You could use gzero, it ignores written data and produces read data with
memset.

> Also, are you thinking setting the hz to some other setting, and
> rerunning?  What setting were you thinking?  I can easily try anything.=


Yes. Try 1500.


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