Date: Mon, 22 Sep 2014 16:07:16 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-hackers@freebsd.org Cc: Bret Ketchum <bcketchum@gmail.com>, Adrian Chadd <adrian@freebsd.org>, Alexander Motin <mav@freebsd.org> Subject: Re: 9.1 callout behavior Message-ID: <3348399.yonqFcmVBb@ralph.baldwin.cx> In-Reply-To: <CAJ-Vmom%2BFGB2OCBr9hwvZDL%2B44-fKhM7m97AvCSmN5nB6da%2BhQ@mail.gmail.com> References: <CAGm6yaTEFECTYVb94A13TaXMPSLtKLpTbw4iNdgd8SuNF1QDaA@mail.gmail.com> <52A731FD.8060307@FreeBSD.org> <CAJ-Vmom%2BFGB2OCBr9hwvZDL%2B44-fKhM7m97AvCSmN5nB6da%2BhQ@mail.gmail.com>
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On Tuesday, September 16, 2014 04:17:20 PM Adrian Chadd wrote: > Hi! > > I know this is bringing up an old thread, but Dell has shipped us some > hardware (thanks Dell!) and I'm helping them take a look at it. > > On 10 December 2013 07:23, Alexander Motin <mav@freebsd.org> wrote: > > On 10.12.2013 17:12, Bret Ketchum wrote: > >> Do either of you have a dual socket/package motherboard to play > >> > >> with? I've tried a couple single socket motherboards and cannot > >> reproduce the issue. I'm wondering if this occurs on only multi-socket > >> mobos. > > > > My main test system is dual-socket (Supermicro X8DTU). > > It's reasonably reproducable. > > The tscdrift tool from jhb (in tools/tools/tscdrift) looks thus: > > root@appollyon:~/src/tscdrift # ./tscdrift > > CPU | TSC skew (min/avg/max/stddev) > > ----+------------------------------ > > 0 | 0 0 0 0.000 > 1 | 34 79 380 39.005 > 2 | 306 476 1326 120.472 > 3 | 306 485 1426 123.487 > 4 | 280 473 7500 248.965 > 5 | 280 462 1320 126.691 > 6 | 300 461 1934 129.362 > 7 | 300 470 1354 122.654 > 8 | 292 420 3640 152.029 > 9 | 135 190 655 58.601 > 10 | 112 188 620 56.490 > 11 | 114 189 660 62.440 > 12 | 129 204 566 53.731 > 13 | 129 206 617 56.047 > 14 | 126 211 620 54.450 > 15 | 126 213 603 54.808 > 16 | 440 590 1683 217.649 > 17 | 440 612 1606 234.295 > 18 | 468 642 4017 266.768 > 19 | 463 653 8683 352.624 > 20 | 480 671 1500 255.395 > 21 | 480 689 8060 348.384 > 22 | 468 707 3766 296.721 > 23 | 466 703 1683 284.625 > 24 | 480 767 8183 373.741 > 25 | 486 782 7400 362.069 > 26 | 480 664 1620 249.125 > 27 | 477 686 3669 278.144 > 28 | 469 621 1897 226.673 > 29 | 469 649 8275 363.575 > 30 | 457 636 1835 250.005 > 31 | 451 641 4300 272.322 FYI, that looks fairly typical for a system whose TSC's are in sync in my experience. Is this a dual-package system? The fact that threads 9-15 are "closer" to 0 than 2-8 is a bit unusual, but the rest looks quite typical. -- John Baldwin
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