From owner-svn-src-stable@freebsd.org Thu Apr 12 20:01:23 2018 Return-Path: Delivered-To: svn-src-stable@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 C9041F8BE49; Thu, 12 Apr 2018 20:01:22 +0000 (UTC) (envelope-from rysto32@gmail.com) Received: from mail-yw0-x243.google.com (mail-yw0-x243.google.com [IPv6:2607:f8b0:4002:c05::243]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 31F4382CBA; Thu, 12 Apr 2018 20:01:22 +0000 (UTC) (envelope-from rysto32@gmail.com) Received: by mail-yw0-x243.google.com with SMTP id y64so2557860ywa.3; Thu, 12 Apr 2018 13:01:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=JBGwRErUzD8UGzo3fo25U9FYL9DYfAcdhDA4Z0U6MJI=; b=hjB6UXTs0vleIsKdVPd5XL00ix5YGFSM872J99A/oRS60jc8npVmIaX+jxLaZ0lW1s GTpBAFqrhlrs5dXjGhv27/m1pGDdLxkFIBhr38bt4Qrb6zz/34/eAbGI3Dzg6z0Apyw2 Ah1H2UvQVi8xNoEtlR06qKtUwACfnc/bxwuZUh7fjn8+vhrw5V9RH5fu6E7GOSZh5xDo L6dcEFIOoOgCP2U8WxN73gUPdv+3i11smMi2hytYwiCTfLIF6XvypXklZYUk9sefvFlF /MLFmHjmeSgfJzVPzwUOqiffHBozKIeYi2qXV2NJMlcVVAuWaJyiaM5TWtIAbxYG6BD9 MilA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=JBGwRErUzD8UGzo3fo25U9FYL9DYfAcdhDA4Z0U6MJI=; b=c/MT9OoX/Fo8Wn3iefIgz3mMKB+aotPgAvsKw7SuC/OXXJsbDoXthdVCvEzq7OycR1 NwONVgJ4stEtaWrT28W61NS6Gc5GKppaW6sUvRW6iYvmyihx2FQPoK09PLMTQ6yUokAR +wLA96t7ttTuPbcvg+ES5ooKZUnQoNyU5y0jDpASkvNw8rh+EgP4L3xIdkutdEGIApZc nzWHrvgdV71F9F5Hha36nc+l7wZW9U+M9K16llXqpyiZXxJkNcnCJ9yCNRgFol9UQUOh XJ8k8HyoK84I8r4wv03DtGSmAmvprmA1hpsWisJAHM29jdtFuLLZCqz9BDfEGC9FkY0x t7gg== X-Gm-Message-State: ALQs6tC+U81dQOZcVGeu2lv+8UKwnoi2jMpzdzMXqDAKZJUYdgh4044I rUk8to5vyQACbLbh0qWnxoYZVIUNDMhn2jLhi+o= X-Google-Smtp-Source: AIpwx486N1Dr2JTFTuGSPnb8p24D1PDJvg4Bb2EVCXBJqulHyH8sS2FLJtBrYWpFz0wKzhTj776Q0khTbrkuVc7Xun8= X-Received: by 10.129.117.70 with SMTP id q67mr1521383ywc.84.1523563281127; Thu, 12 Apr 2018 13:01:21 -0700 (PDT) MIME-Version: 1.0 Received: by 10.200.81.207 with HTTP; Thu, 12 Apr 2018 13:01:20 -0700 (PDT) In-Reply-To: <201804121906.w3CJ6FZo092138@repo.freebsd.org> References: <201804121906.w3CJ6FZo092138@repo.freebsd.org> From: Ryan Stone Date: Thu, 12 Apr 2018 16:01:20 -0400 Message-ID: Subject: Re: svn commit: r332447 - stable/11/sys/dev/ixgbe To: Stephen Hurd Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Content-Type: text/plain; charset="UTF-8" X-BeenThere: svn-src-stable@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: SVN commit messages for all the -stable branches of the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 12 Apr 2018 20:01:23 -0000 Spinning in the kernel for a full second is a really bad idea. At minimum this is going to hold off all callouts from one of the callout threads for up to a full second as ixgbe_local_timer() waits for the core mutex. That chews up two CPU cores doing busy-wait loops (the ixgbe_stop() thread busy-waits in msec_delay and the callout thread adaptively spins waiting for the mutex). If any other thread tries to acquire the core lock they also adaptively spin on the mutex chewing up yet more cores. This includes any threads trying to fetch interface status (e.g. ifconfig), various interrupt handlers, etc.