Alberto García

O Grove (Spain), 1978

One of the founding members of Igalia, Alberto loves computing since he got his first ZX Spectrum in the early nineties.

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Alberto García 08/02/2017

QEMU and the qcow2 metadata checks

When choosing a disk image format for your virtual machine one of the factors to take into considerations is its I/O performance. In this post I’ll talk a bit about the internals of qcow2 and about one of the aspects that can affect its performance...

Alberto García 24/05/2016

I/O bursts with QEMU 2.6

QEMU 2.6 was released a few days ago. One new feature that I have been working on is the new way to configure I/O limits in disk drives to allow bursts and increase the responsiveness of the virtual machine. In this post I’ll try to explain how it...

Alberto García 17/12/2015

Improving disk I/O performance in QEMU 2.5 with the qcow2 L2 cache

QEMU 2.5 has just been released, with a lot of new features. As with the previous release, we have also created a video changelog. I plan to write a few blog posts explaining some of the things I have been working on. In this one I’m going to talk...

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qcow2: Make perform_cow() call do_perform_cow() twice

qcow2: Make perform_cow() call do_perform_cow() twice Instead of calling perform_cow() twice with a different COW region each time, call it just once and make perform_cow() handle both regions. This patch simply moves code around. The next one will do...

Alberto García26/06/2017

qcow2: Use unsigned int for both members of Qcow2COWRegion

qcow2: Use unsigned int for both members of Qcow2COWRegion Qcow2COWRegion has two attributes: - The offset of the COW region from the start of the first cluster touched by the I/O request. Since it's always going to be positive and the maximum...

Alberto García26/06/2017

qcow2: Remove unused Error variable in do_perform_cow()

qcow2: Remove unused Error variable in do_perform_cow() We are using the return value of qcow2_encrypt_sectors() to detect problems but we are throwing away the returned Error since we have no way to report it to the user. Therefore we can simply get...

Alberto García26/06/2017

throttle: Update throttle-groups.c documentation

throttle: Update throttle-groups.c documentation There used to be throttle_timers_{detach,attach}_aio_context() calls in bdrv_set_aio_context(), but since 7ca7f0f6db1fedd28d490795d778cf239 they are now in blk_set_aio_context(). Signed-off-by: Alberto...

Alberto García26/06/2017

qcow2: remove extra local_error variable

qcow2: remove extra local_error variable Commit d7086422b1c1e75e320519cfe26176db6ec97a37 added a local_err variable global to the qcow2_amend_options() function, so there's no need to have this other one. Signed-off-by: Alberto Garcia Message-id:...

Alberto García30/05/2017