From mboxrd@z Thu Jan 1 00:00:00 1970 From: mulyadi.santosa@gmail.com (Mulyadi Santosa) Date: Fri, 3 Feb 2012 12:59:29 +0700 Subject: blktrace vs ftrace In-Reply-To: <4F2ADEC9.1090200@gmail.com> References: <4F2A6357.3060805@gmail.com> <4F2ADEC9.1090200@gmail.com> Message-ID: To: kernelnewbies@lists.kernelnewbies.org List-Id: kernelnewbies.lists.kernelnewbies.org Hi :) On Fri, Feb 3, 2012 at 02:06, Matthias Brugger wrote: > > qemu -hda scheduler.raw -drive > file=/mnt/disk/testdisk2.img,if=virtio,cache=none -m 1024 -enable-kvm -k es > -smp 2 -vnc 127.0.0.1:10 -smb /home/matthias/nfs/ > > > I use qemu-0.15.1 configured with the following parameter: > > ./configure --disable-xen re--enable-kvm --enable-io-thread > --enable-vnc-thread --disable-darwin-user --disable-bsd-user > --target-list=i386-softmmu Looks like indeed you were seeing I/O threads from qemu kicks in. I could only offer this explanation: blktrace traces events in block level. In this level, I/O is likely serialized....unless you have more than one physical disks. in ftrace, you see events right before it hits block level operation. Somewhere between VFS, filesystem operation and I/O scheduling which deals with queue reordering. In this case, parallel operation is likely to happen because more than processes could submit read or write. -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com