i386/135447: [i386] [request] Intel Core i7 and Nehalem-EP new
features not supported
Alexander Motin
mav at FreeBSD.org
Thu Sep 23 12:40:02 UTC 2010
The following reply was made to PR i386/135447; it has been noted by GNATS.
From: Alexander Motin <mav at FreeBSD.org>
To: Dmitry Kubov <dk at garant.ru>
Cc: Andriy Gapon <avg at FreeBSD.org>, jh at FreeBSD.org,
bug-followup <bug-followup at FreeBSD.org>
Subject: Re: i386/135447: [i386] [request] Intel Core i7 and Nehalem-EP new
features not supported
Date: Thu, 23 Sep 2010 15:34:23 +0300
Dmitry Kubov wrote:
>> It would be
>> interesting to repeat same test if you updated to 8-STABLE or at least
>> apply patch from SVN rev 209897 on 2010-07-11 11:58:46Z.
>
> New system:
> CPU: Intel(R) Xeon(R) CPU X5680 @ 3.33GHz (3333.47-MHz
> K8-class CPU)
> FreeBSD/SMP: Multiprocessor System Detected: 12 CPUs
> FreeBSD/SMP: 2 package(s) x 6 core(s)
> HT disabled in BIOS.
This CPU has only 266MHz TurboBoost speedup. And some part of it
(probably half) could be enabled all the time. This benefit still could
be overweighted by C-states latencies penalty. It could be interesting
to test some other workloads, like compilation with different number of
threads.
> Note 3333/3334 difference:
> TurboBoost disabled:
> dev.cpu.0.freq: 3333
> dev.cpu.0.freq_levels: 3333/130000 3200/117000 3067/105000 2933/94000
> 2800/85000
> 2667/76000 2533/68000 2400/61000 2267/54000 2133/48000 2000/43000
> 1867/39000 17
> 33/35000 1600/32000 1400/28000 1200/24000 1000/20000 800/16000 600/12000
> 400/8000 200/4000
> dev.est.0.freq_settings: 3333/130000 3200/117000 3067/105000 2933/94000
> 2800/850
> 00 2667/76000 2533/68000 2400/61000 2267/54000 2133/48000 2000/43000
> 1867/39000 1733/35000 1600/32000
>
> TurboBoost enabled:
> dev.cpu.0.freq: 3334
> dev.cpu.0.freq_levels: 3334/143000 3200/117000 3067/105000 2933/94000
> 2800/85000
> 2667/76000 2533/68000 2400/61000 2267/54000 2133/48000 2000/43000
> 1867/39000 17
> 33/35000 1600/32000 1400/28000 1200/24000 1000/20000 800/16000 600/12000
> 400/8000 200/4000
> dev.est.0.freq_settings: 3334/143000 3333/130000 3200/117000 3067/105000
> 2933/94
> 000 2800/85000 2667/76000 2533/68000 2400/61000 2267/54000 2133/48000
> 2000/43000 1867/39000 1733/35000 1600/32000
Intel writes that BIOS may report additional P-state with 1MHz
difference, to allow OS to control TurboBoost. It's just cpufreq
subsystem behavior/limitation to drop very close frequencies. Actually I
am not sure how this additional P-state could be used, except for testing.
> In short: no 60% disk io performance drop in 8.1-STABLE. Other tests
> give same results like 8.1-RELEASE, 5% average cpu performance drop.
Disk performance fix is reasonable. Some recent improvements in
9-CURRENT should improve it even more. What's about ubench - try some
different load.
--
Alexander Motin
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