From owner-svn-src-all@freebsd.org Fri May 24 23:21:52 2019 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 9E7A915B7A9C for ; Fri, 24 May 2019 23:21:52 +0000 (UTC) (envelope-from steven@multiplay.co.uk) Received: from mail-lj1-x22f.google.com (mail-lj1-x22f.google.com [IPv6:2a00:1450:4864:20::22f]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smtp.gmail.com", Issuer "GTS CA 1O1" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 2767C842DA for ; Fri, 24 May 2019 23:21:52 +0000 (UTC) (envelope-from steven@multiplay.co.uk) Received: by mail-lj1-x22f.google.com with SMTP id r76so4562305lja.12 for ; Fri, 24 May 2019 16:21:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=multiplay-co-uk.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=OaRPxNiOZGgeK3Rq556SEPDaQoEviIzR8r/qchDg3MM=; b=YeOKaOABZrHa3DONQMgV7WJttpQNmpbIQaoBQ834xvrwoIb1gmrt62pw4EmEK1OGqV xk7P+OfIU/1Ls1yWj7/46l5n7hIMOqzhKIRQ8WNCgrJn1yiaEzGQJSf1o7UAn0xORihC j+dDXwupjohRUCETysp9y9/9u90SxUe+iFAoRTkmXu3+rjYverqexlkzipvK5rSUeGCj Z7mXUwbWQY2LQWMGnwGMd3g9d+BWXwtFYKpJLianR/0cqWSU6FJ84VGJFyFdzGES5h/Q tooeQEW4zWrISKf4RJvmhbDSLR0yAgcu0poRic8Um3++ehZqjX12bAUGVEYFZSah/qHf iGkw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=OaRPxNiOZGgeK3Rq556SEPDaQoEviIzR8r/qchDg3MM=; b=Qp+VHoHiXFY9aT5y3maE0EKeVTq8d63eLbkPBuUbWYIAEN+rymoPrNXMkqcpT9uPw0 s8MsnPEFcvollweXI0qGPn/oj17Blw2dZAZHLdorT53/lXu5EJKxvVB3vnTONBLgMLoQ m98ctaMZzy9z/H4eLw84CrQ1X6GmcSmgK1ILyoKseKL8R/nTVHrxCHpf3n6Watraurzy mnnHxeG3ir0rbnpMKuYG9xPvkKOTxIHj57EzR7p65Ilpm0PeWP74ArvUnVD0Q03LSoTU bvqfnnfDpw9xSHNqAYPbszZg8xMn9+k4mM9LaCdebBkfxjrCXaqxdTP6PH+fv3VE7OJ0 51yg== X-Gm-Message-State: APjAAAW4UTXDC0hkNN11vcCNQt4HmRgIWlZLybk2jRe14AFDptN7KWCo k9s4Jo51AXH4rhi5dnoEBQY+GepE+j/rfBUay7E1HQ== X-Google-Smtp-Source: APXvYqyFnx0r5KfvFTzQSTP/J/X5a3UwgK0+LvoxVCrDJWlHM7UKOhR8fipwJT2QJls/NI9z6Id6YMze1XFv8HnT/kc= X-Received: by 2002:a2e:90d1:: with SMTP id o17mr40556440ljg.187.1558740110030; Fri, 24 May 2019 16:21:50 -0700 (PDT) MIME-Version: 1.0 References: <201905242233.x4OMXEAr071844@repo.freebsd.org> In-Reply-To: <201905242233.x4OMXEAr071844@repo.freebsd.org> From: Steven Hartland Date: Sat, 25 May 2019 00:21:39 +0100 Message-ID: Subject: Re: svn commit: r348255 - head/sys/kern To: Conrad Meyer Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org X-Rspamd-Queue-Id: 2767C842DA X-Spamd-Bar: ------ Authentication-Results: mx1.freebsd.org X-Spamd-Result: default: False [-6.96 / 15.00]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; NEURAL_HAM_SHORT(-0.96)[-0.964,0]; REPLY(-4.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000,0] Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.29 X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 24 May 2019 23:21:52 -0000 Just wanted to say I really appreciate the details in this commit message. Its often the case the message get overlooked when it comes to the time needed to write a truly useful message to others and this a great example of the quality we should all try to follow. Regards Steve On Fri, 24 May 2019 at 23:33, Conrad Meyer wrote: > Author: cem > Date: Fri May 24 22:33:14 2019 > New Revision: 348255 > URL: https://svnweb.freebsd.org/changeset/base/348255 > > Log: > Disable intr_storm_threshold mechanism by default > > The ixl.4 manual page has documented that the threshold falsely detects > interrupt storms on 40Gbit NICs as long ago as 2015, and we have seen > similar false positives with the ioat(4) DMA device (which can push > GB/s). > > For example, synthetic load can be generated with tools/tools/ioat > 'ioatcontrol 0 200 8192 1 1000' (allocate 200x8kB buffers, generate an > interrupt for each one, and do this for 1000 milliseconds). With > storm-detection disabled, the Broadwell-EP version of this device is > capable > of generating ~350k real interrupts per second. > > The following historical context comes from jhb@: Originally, the > threshold > worked around incorrect routing of PCI INTx interrupts on single-CPU > systems > which would end up in a hard hang during boot. Since the threshold was > added, our PCI interrupt routing was improved, most PCI interrupts use > edge-triggered MSI instead of level-triggered INTx, and typical systems > have > multiple CPUs available to service interrupts. > > On the off chance that the threshold is useful in the future, it remains > available as a tunable and sysctl. > > Reviewed by: jhb > Sponsored by: Dell EMC Isilon > Differential Revision: https://reviews.freebsd.org/D20401 > > Modified: > head/sys/kern/kern_intr.c > > Modified: head/sys/kern/kern_intr.c > > ============================================================================== > --- head/sys/kern/kern_intr.c Fri May 24 22:30:40 2019 (r348254) > +++ head/sys/kern/kern_intr.c Fri May 24 22:33:14 2019 (r348255) > @@ -91,7 +91,7 @@ struct proc *intrproc; > > static MALLOC_DEFINE(M_ITHREAD, "ithread", "Interrupt Threads"); > > -static int intr_storm_threshold = 1000; > +static int intr_storm_threshold = 0; > SYSCTL_INT(_hw, OID_AUTO, intr_storm_threshold, CTLFLAG_RWTUN, > &intr_storm_threshold, 0, > "Number of consecutive interrupts before storm protection is > enabled"); > >