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: 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

stream: fix crash in stream_start() when block_job_create() fails

stream: fix crash in stream_start() when block_job_create() fails The code that tries to reopen a BlockDriverState in stream_start() when the creation of a new block job fails crashes because it attempts to dereference a pointer that is known to be...

Alberto García30/05/2017

qemu-doc: Clarify that -vga std is now the default

qemu-doc: Clarify that -vga std is now the default The QEMU manual page states that Cirrus Logic is the default video card if the user doesn't specify any. However this is not true since QEMU 2.2. Signed-off-by: Alberto Garcia Message-Id:...

Alberto García16/02/2017

qemu-io: don't allow I/O operations larger than BDRV_REQUEST_MAX_BYTES

qemu-io: don't allow I/O operations larger than BDRV_REQUEST_MAX_BYTES Passing a request size larger than BDRV_REQUEST_MAX_BYTES to any of the I/O commands results in an error. While 'read' and 'write' handle the error correctly,...

Alberto García13/02/2017

qcow2: Optimize the refcount-block overlap check

qcow2: Optimize the refcount-block overlap check The metadata overlap checks introduced in a40f1c2add help detect corruption in the qcow2 image by verifying that data writes don't overlap with existing metadata sections. The...

Alberto García13/02/2017