From: bugzilla-daemon@bugzilla.kernel.org
Subject: [Bug 14972] [regression] msync() call on ext4 causes disk thrashing
Date: Mon, 4 Jan 2010 03:35:24 GMT
Message-ID: <201001040335.o043ZOrW020607@demeter.kernel.org>
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Eric Sandeen changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |sandeen@redhat.com
--- Comment #10 from Eric Sandeen 2010-01-04 03:35:22 ---
(In reply to comment #9)
> grep BLK.*TRACE /usr/src/linux/.config
>
> CONFIG_BLK_DEV_IO_TRACE=y
>
> Yes, I'm running under root. SeLinux is disabled in the kernel. I've no idea
> what to do :(
Drop the echos. Just mounting debugfs & running blktrace will suffice:
[root@inode ~]# mount -t debugfs none /sys/kernel/debug/
[root@inode ~]# blktrace /dev/sda
^C=== sda ===
CPU 0: 0 events, 0 KiB data
CPU 1: 1 events, 1 KiB data
Total: 1 events (dropped 0), 1 KiB data
but if you do this first:
[root@inode ~]# echo blk > /sys/kernel/debug/tracing/current_tracer
[root@inode ~]# echo 1 > /sys/block/sda/sda3/trace/enable
you get the -EBUSY:
[root@inode ~]# blktrace /dev/sda
BLKTRACESETUP(2) /dev/sda failed: 16/Device or resource busy
Thread 1 failed open /sys/kernel/debug/block/(null)/trace1: 2/No such file or
directory
Thread 0 failed open /sys/kernel/debug/block/(null)/trace0: 2/No such file or
directory
FAILED to start thread on CPU 0: 1/Operation not permitted
FAILED to start thread on CPU 1: 1/Operation not permitted
It's not related to selinux.
-Eric
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