From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2992831AbbHIAH1 (ORCPT ); Sat, 8 Aug 2015 20:07:27 -0400 Received: from mail1.windriver.com ([147.11.146.13]:61227 "EHLO mail1.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2992728AbbHIAHZ (ORCPT ); Sat, 8 Aug 2015 20:07:25 -0400 Date: Sat, 8 Aug 2015 20:06:59 -0400 From: Paul Gortmaker To: Steven Rostedt CC: , linux-rt-users , Thomas Gleixner , Carsten Emde , Sebastian Andrzej Siewior , John Kacur Subject: Re: [PATCH RT 0/6] Linux 3.14.48-rt49-rc1 Message-ID: <20150809000659.GH5998@windriver.com> References: <20150806221736.555188732@goodmis.org> <20150808231017.GG5998@windriver.com> <20150808192346.740ece60@grimm.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20150808192346.740ece60@grimm.local.home> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [Re: [PATCH RT 0/6] Linux 3.14.48-rt49-rc1] On 08/08/2015 (Sat 19:23) Steven Rostedt wrote: > On Sat, 8 Aug 2015 19:10:17 -0400 > Paul Gortmaker wrote: > > > > So we took 20 IRQs in 5s, or 4/s ; not quite the 1/s minimum, but definitely not > > the HZ/s we'd get w/o NOHZ_FULL. Re-running it got consistently 18-20 IRQ / 5s. > > OK, so NO_HZ_FULL still isn't great on -rt, but this shows that it > keeps disturbances much lower than without it. Here is several runs on vanilla ("make oldconfig" of the -rt .config) and all else (bootargs, isolation, rcu offload) the same: -------------------------------------------------- root@testbox:/home/paul# ./t LOC: 86341 740 724 708 694 679 663 649 633 619 545 526 512 494 481 463 448 434 420 404 Local timer interrupts LOC: 91349 742 727 708 694 679 663 649 633 619 545 526 512 496 483 465 450 436 423 406 Local timer interrupts LOC: 96353 742 727 710 697 709 665 651 635 622 547 528 514 496 483 465 450 436 423 406 Local timer interrupts root@testbox:/home/paul# ./t LOC: 106188 744 729 712 699 711 667 653 638 624 549 530 514 498 485 467 452 438 425 408 Local timer interrupts LOC: 111194 746 729 712 699 711 667 653 638 624 549 530 516 500 487 469 454 440 427 410 Local timer interrupts LOC: 116199 746 731 714 701 729 669 655 640 626 551 532 516 500 487 469 454 440 427 410 Local timer interrupts root@testbox:/home/paul# ./t LOC: 122860 748 733 716 703 731 669 655 640 626 551 532 518 502 489 471 456 442 429 412 Local timer interrupts LOC: 127866 748 733 716 703 731 671 657 642 628 553 534 520 504 492 473 456 442 429 412 Local timer interrupts LOC: 132872 750 735 718 706 748 671 657 642 628 553 534 520 504 492 473 458 444 431 415 Local timer interrupts root@testbox:/home/paul# cat /proc/version Linux version 3.14.48 (paul@yow-dellw-pg2) (gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1) ) #2 SMP PREEMPT Sat Aug 8 19:52:12 EDT 2015 root@testbox:/home/paul# -------------------------------------------------- So 30, 18, and 17 per 5s interval. I'd say that is statisitcally close enough to -rt on this simple test to call -rt on par with vanilla. Things might show a difference with more complicated tests, more cores doing real work etc etc. -- this really is just a simple sanity test though... but at least it is a test that we now can pass! Paul. -- > > Thanks for the report! > > -- Steve > > > > > I specifically did NOT unplug and replug cores to "clean" them of tasks; the > > hotplug code just seems to unstable for that from what I've seen in the past, > > and by the looks of the irq counts above, there was no need to either. > > > > The rootfs was basically a ubu 14.10 server install (no X11/gfx) -- not that > > it should matter - so long as other tasks weren't running on the nohz cores. > > > > Paul. > > -- > > > > > > > > Enjoy, > > > > > > -- Steve > > > >