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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