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Date:      Sun, 16 Mar 2003 13:41:24 -0800
From:      Brooks Davis <brooks@one-eyed-alien.net>
To:        Andy Isaacson <adi@hexapodia.org>
Cc:        Brooks Davis <brooks@one-eyed-alien.net>, smp@freebsd.org
Subject:   Re: weird power usage on dual Xeon
Message-ID:  <20030316134124.B4374@Odin.AC.HMC.Edu>
In-Reply-To: <20030315010321.A12293@hexapodia.org>; from adi@hexapodia.org on Sat, Mar 15, 2003 at 01:03:21AM -0600
References:  <20030314174113.A16583@Odin.AC.HMC.Edu> <20030315010321.A12293@hexapodia.org>

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On Sat, Mar 15, 2003 at 01:03:21AM -0600, Andy Isaacson wrote:
>=20
> Do you get a different answer if you run only two copies of SETI?  I
> can't imagine that their FFT routine takes kindly to having to share L1
> cache, perhaps it's spending all its time waiting for the L2... and do
> you actually process more work units per hour with 4 SETI processes
> running on HT as opposed to 2 SETIs without HT?  I kinda doubt it, but
> would welcome real information.

Given the way our schedular handles HTT (it doesn't) you're just
as likely to end up with two SETI procs on one CPU as with them on
different CPUs.  In any case, SETI actually gets fairly significantly
better results when you run four with HTT enabled then when you run two
without.  With two I'm seeing about 4hr per workunit or one every 2hrs,
with four I'm seeing about 6hrs per workunit or one every 1.5hrs.

-- Brooks

--=20
Any statement of the form "X is the one, true Y" is FALSE.
PGP fingerprint 655D 519C 26A7 82E7 2529  9BF0 5D8E 8BE9 F238 1AD4

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