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[Qemu-devel] xen_disk qdevification (was: [PATCH 0/3] Performance improv

From: Kevin Wolf
Subject: [Qemu-devel] xen_disk qdevification (was: [PATCH 0/3] Performance improvements for xen_disk v2)
Date: Fri, 2 Nov 2018 12:04:12 +0100
User-agent: Mutt/1.10.1 (2018-07-13)

Am 02.11.2018 um 11:00 hat Tim Smith geschrieben:
> A series of performance improvements for disks using the Xen PV ring.
> These have had fairly extensive testing.
> The batching and latency improvements together boost the throughput
> of small reads and writes by two to six percent (measured using fio
> in the guest)
> Avoiding repeated calls to posix_memalign() reduced the dirty heap
> from 25MB to 5MB in the case of a single datapath process while also
> improving performance.
> v2 removes some checkpatch complaints and fixes the CCs

Completely unrelated, but since you're the first person touching
xen_disk in a while, you're my victim:

At KVM Forum we discussed sending a patch to deprecate xen_disk because
after all those years, it still hasn't been converted to qdev. Markus is
currently fixing some other not yet qdevified block device, but after
that xen_disk will be the only one left.

A while ago, a downstream patch review found out that there are some QMP
commands that would immediately crash if a xen_disk device were present
because of the lacking qdevification. This is not the code quality
standard I envision for QEMU. It's time for non-qdev devices to go.

So if you guys are still interested in the device, could someone please
finally look into converting it?


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