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[209.132.180.67]) by mx.google.com with ESMTP id a6si717279pll.406.2017.09.21.02.04.41; Thu, 21 Sep 2017 02:04:41 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=U+5m9BNh; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751892AbdIUJEj (ORCPT + 26 others); Thu, 21 Sep 2017 05:04:39 -0400 Received: from mail-wm0-f48.google.com ([74.125.82.48]:50324 "EHLO mail-wm0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751521AbdIUJEh (ORCPT ); Thu, 21 Sep 2017 05:04:37 -0400 Received: by mail-wm0-f48.google.com with SMTP id v142so13503194wmv.5 for ; Thu, 21 Sep 2017 02:04:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id; bh=zCjnpw4N5+7703xTVmxdkdAd9ltLo4jk93GKvNXNRFc=; b=U+5m9BNhCxIwVmUilRRMYRw7IqdeyHO7WDj+T36ryM86cbIMUtAFQ2M7BfBDX3HuPQ c0nUwBaLwBvNgOe1Ao6FSkHUG9re2GsNOxETkLsW1rP80QDOfliKpAvbhf/dvMf+uZLs R2+qZ+4IG4a6LfUIWiYuTTwoQOfKNpCAtqq14= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=zCjnpw4N5+7703xTVmxdkdAd9ltLo4jk93GKvNXNRFc=; b=XxBYBUVSI8xq4LORjsM+jZ/Yd4k7gzIWb4m9DA6w+jp4ZWV0LgFqmiJ39+CsbiBS1L or8jguDSzI5rF9YXveJ0ZjqSxyP14UazMzsFhlLgAmrRf+q9Alfk0XevigGUt3iRGMh2 +ak2pjPYmdXQIfEsJZVs94Ntp5QDiYITeIqmOTj81jPRx3D0P1JX33eTzCSDlPnK6U5P QGdIVJBaNQWnQlAv7TyT2m4h0QYR4knZ36nVWF/w4UU4hbX94u6x/56t/5xTuSC2Gv84 EFY0qIsiD5RBDHHcaTjCN0Nd2phRs5hVAzxVNlwGQA6DZxpwm6uoVeMHWFRlTVKbLLyl U4+w== X-Gm-Message-State: AHPjjUhuoWcczVeUXzp9as+Gi1z8FefzrEFScG5rOokRCE8sLYPi8ywL IWGbDuVFuvICg5ZCKvjd6w4MWA== X-Google-Smtp-Source: AOwi7QAJobh6jixOxebWZrZPQ3h8H8y88rrGt3ySyPzRyUhFofm9QDSe8IMry1tDlElrsh9m+HjYhw== X-Received: by 10.28.59.215 with SMTP id i206mr343986wma.116.1505984676310; Thu, 21 Sep 2017 02:04:36 -0700 (PDT) Received: from localhost.localdomain ([185.14.11.73]) by smtp.gmail.com with ESMTPSA id o59sm804032wrc.45.2017.09.21.02.04.34 (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 21 Sep 2017 02:04:35 -0700 (PDT) From: Paolo Valente To: Jens Axboe Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, ulf.hansson@linaro.org, broonie@kernel.org, lee.tibbert@gmail.com, oleksandr@natalenko.name, mirkomontanari91@gmail.com, angeloruocco90@gmail.com, mauro.andreolini@unimore.it, Paolo Valente Subject: [PATCH BUGFIX/IMPROVEMENT 0/4] block, bfq: series of fixes of bugs affecting service guarantees Date: Thu, 21 Sep 2017 11:03:59 +0200 Message-Id: <20170921090403.3217-1-paolo.valente@linaro.org> X-Mailer: git-send-email 2.10.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, the first patch in this series fixes a bug that causes bfq to fail to guarantee a high responsiveness on some drives, if there is heavy random read+write I/O in the background. More precisely, such a failure allowed this bug to be found [1], but the bug may well cause other yet unreported anomalies. This fix uncovered other bugs that were concealed by the fixed bug, for rather subtle reasons. These further bugs caused similar responsiveness failures, but with sequential reaad+write workloads in the background. The remaining three patches fix these further bugs. The sum of these fixes makes responsiveness much stabler with BFQ. In the presence of write hogs, it is however still impossible for an I/O scheduler to guarantee perfect responsiveness in any circustance, because of throttling issues in the virtual-memory management subsystem, and in other higher-level components. Thanks, Paolo [1] Background I/O Type: Random - Background I/O mix: Reads and writes - Application to start: LibreOffice Writer in http://www.phoronix.com/scan.php?page=news_item&px=Linux-4.13-IO-Laptop Paolo Valente (4): block, bfq: fix wrong init of saved start time for weight raising block, bfq: check and switch back to interactive wr also on queue split block, bfq: let early-merged queues be weight-raised on split too block, bfq: decrease burst size when queues in burst exit block/bfq-iosched.c | 169 +++++++++++++++++++++++++++++++--------------------- 1 file changed, 102 insertions(+), 67 deletions(-) -- 2.10.0