Alberto García

O Grove (Spain)

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

Latest Updates

Alberto García 16/11/2017

“Improving the performance of the qcow2 format” at KVM Forum 2017

I was in Prague last month for the 2017 edition of the KVM Forum. There I gave a talk about some of the work that I’ve been doing this year to improve the qcow2 file format used by QEMU for storing disk images. The focus of my work is to make qcow2...

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...

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qemu-iotests: Update 093 to improve the draining test

qemu-iotests: Update 093 to improve the draining test The previous patch fixes a problem in which draining a block device with more than one throttled request can make it wait first for the completion of requests in other members of the same...

Alberto García16/08/2018

throttle-groups: Skip the round-robin if a member is being drained

throttle-groups: Skip the round-robin if a member is being drained In the throttling code after an I/O request has been completed the next one is selected from a different member using a round-robin algorithm. This ensures that all members get a chance...

Alberto García16/08/2018

qemu-iotests: Test removing a throttle group member with a pending timer

qemu-iotests: Test removing a throttle group member with a pending timer A throttle group can have several members, and each one of them can have several pending requests in the queue. The requests are processed in a round-robin fashion, so the...

Alberto García16/08/2018

block: Simplify append_open_options()

block: Simplify append_open_options() This function returns a BDS's driver-specific options, excluding also those from its children. Since we have just removed all children options from bs->options there's no need to do this last step. We...

Alberto García16/08/2018

throttle: Fix crash on reopen

throttle: Fix crash on reopen The throttle block filter can be reopened, and with this it is possible to change the throttle group that the filter belongs to. The way the code does that is the following: - On throttle_reopen_prepare(): create a new...

Alberto García11/06/2018