From owner-freebsd-current@freebsd.org Thu Apr 14 22:42:34 2016 Return-Path: Delivered-To: freebsd-current@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id CE7F4AEC221 for ; Thu, 14 Apr 2016 22:42:34 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: from mail-ig0-x22a.google.com (mail-ig0-x22a.google.com [IPv6:2607:f8b0:4001:c05::22a]) (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 9AE4A1D2F for ; Thu, 14 Apr 2016 22:42:34 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: by mail-ig0-x22a.google.com with SMTP id g8so6715988igr.0 for ; Thu, 14 Apr 2016 15:42:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bsdimp-com.20150623.gappssmtp.com; s=20150623; h=mime-version:sender:date:message-id:subject:from:to; bh=FR/oh7l8wKFLqay2lLArvW5PCffiYSbfF1PK34PqjVk=; b=X2PuvtfFmB0c84QdqmC0AJYTQgnEPpl5um6v+AGA+NS5z+SdGtTClrsvMa1Sqqyzpo GfLH3aTzj8Fjb1SFl9ryzLvwAsTLh5dEwt6LLL40GAX1a5P/c4shYNHLw6JMp1wzMy8U 1G4WypgV0uyGfGShhyY60NmVkt5h5FJyNnYDJQekAFN6jmSow/jJzwDM958azKHOtOE0 kJdbbsHMEpdr0rfmCjCbLqfisBglCEEP658mLMAewgU0oIhvsalVBwJ6Pba/ZpaXocCk +KAUHGCvO+XnzGi7yh+nLu40Am3bd6hG3AaxYQ8QFwXZDrP4L5JySPXRJBW1b0XZd5gj MPfA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:sender:date:message-id:subject:from :to; bh=FR/oh7l8wKFLqay2lLArvW5PCffiYSbfF1PK34PqjVk=; b=eYF0SeuCKwL8NFVb/xZbOMxTjiqDheK6aEjWk8anrIsWtKoLAYF9xl26amM1h8pnfL TZjk+htKeQEdeQzFUMM9zpaBeNFOJzo/zyAo+d0ckOFNRkYvUNoO0nCN8Bq4hC6xWn6J B0RZSre0F+yv5n9OygshA41+YpLWmA0Vm6o4YFXJChVTAUNnuQTEnJqu4gQg7G30RTKa J+faBvZZs9qa+Oiql+v09W8yiJRIXifMGkPuPy/ciNii+XgDuhutyRrlJlO7am/0ahKM XZG1K5RnWEMppLoge9dt8wKkoPE6LQbyTUVc1gXzbiDbIAwSRSBoAmv2MejERayqMJds wrEQ== X-Gm-Message-State: AOPr4FUtRzHEGmO6fXpRSkvYbdUrtXHkPNGP56W2IJO9AZhX5DTAchT6Jkyl2rcFr9boT5VG5vIZq35NRoqquQ== MIME-Version: 1.0 X-Received: by 10.50.108.106 with SMTP id hj10mr1146794igb.36.1460673753917; Thu, 14 Apr 2016 15:42:33 -0700 (PDT) Sender: wlosh@bsdimp.com Received: by 10.36.194.3 with HTTP; Thu, 14 Apr 2016 15:42:33 -0700 (PDT) X-Originating-IP: [50.253.99.174] Date: Thu, 14 Apr 2016 16:42:33 -0600 X-Google-Sender-Auth: jbyB29BTWDz1nLcTjVIn8TMIC8I Message-ID: Subject: Heads up From: Warner Losh To: FreeBSD Current Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.21 X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 14 Apr 2016 22:42:34 -0000 The CAM I/O scheduler has been committed to current. This work is described in https://people.freebsd.org/~imp/bsdcan2015/iosched-v3.pdf though the default scheduler doesn't change the default (old) behavior. One possible issue, however, is that it also enables NCQ Trims on ada SSDs. There are a few rogue drives that claim support for this feature, but actually implement data corrupt instead of queued trims. The list of known rogues is believed to be complete, but some caution is in order. Warner