Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755165Ab3H2DQj (ORCPT ); Wed, 28 Aug 2013 23:16:39 -0400 Received: from mail-pd0-f172.google.com ([209.85.192.172]:53473 "EHLO mail-pd0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752028Ab3H2DQi (ORCPT ); Wed, 28 Aug 2013 23:16:38 -0400 MIME-Version: 1.0 Date: Wed, 28 Aug 2013 20:16:37 -0700 Message-ID: Subject: Possible Bcache Bug From: kernel neophyte To: Kent Overstreet Cc: "linux-kernel@vger.kernel.org" , "linux-bcache@vger.kernel.org" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2892 Lines: 62 Hi Kent, I have configured Bcache as follows: echo /dev/sda3 > /sys/fs/bcache/register echo /dev/sdb1 > /sys/fs/bcache/register echo 5fd1b675-ea67-4039-82f6-caa325d10559 > /sys/block/bcache0/bcache/attach echo 0 > /sys/block/bcache0/bcache/sequential_cutoff echo 0 > /sys/fs/bcache/5fd1b675-ea67-4039-82f6-caa325d10559/congested_read_threshold_us echo 0 > /sys/fs/bcache/5fd1b675-ea67-4039-82f6-caa325d10559/congested_write_threshold_us echo 0 > /sys/fs/bcache/5fd1b675-ea67-4039-82f6-caa325d10559/synchronous echo writeback > /sys/block/bcache0/bcache/cache_mode echo 0 > /sys/block/bcache0/bcache/writeback_running echo 0 > /sys/block/bcache0/bcache/writeback_metadata in other words for I am trying to get some benchmarking numbers by using ssd only ie not use hdd for anything. by doing the above I expected hdd will never be used and all reads and writes will happen to and from the ssd... How ever to my shock random writes started happening to the HDD even iostat confirmed it avg-cpu: %user %nice %system %iowait %steal %idle 0.00 0.00 0.40 16.05 0.00 83.55 Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn sda 236.30 0.00 945.20 0 9452 sdb 0.00 0.00 0.00 0 0 bcache0 236.30 0.00 945.20 0 9452 avg-cpu: %user %nice %system %iowait %steal %idle 0.02 0.00 0.42 16.08 0.00 83.48 Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn sda 226.90 0.00 908.00 0 9080 sdb 0.00 0.00 0.00 0 0 bcache0 226.50 0.00 906.00 0 9060 avg-cpu: %user %nice %system %iowait %steal %idle 0.02 0.00 0.37 16.08 0.00 83.53 Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn sda 235.40 0.00 941.60 0 9416 sdb 0.00 0.00 0.00 0 0 bcache0 235.40 0.00 941.60 0 9416 avg-cpu: %user %nice %system %iowait %steal %idle 0.02 0.00 0.32 16.06 0.00 83.61 Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn sda 238.50 0.00 954.00 0 9540 sdb 0.00 0.00 0.00 0 0 bcache0 238.50 0.00 954.00 0 9540 This looks like a possible bug to me. Could you please confirm ? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/