[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH v5] block: add event when disk usage exceeds thr
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH v5] block: add event when disk usage exceeds threshold |
Date: |
Tue, 13 Jan 2015 13:54:41 +0000 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Mon, Jan 12, 2015 at 02:11:13PM +0100, Francesco Romani wrote:
> Managing applications, like oVirt (http://www.ovirt.org), make extensive
> use of thin-provisioned disk images.
> To let the guest run smoothly and be not unnecessarily paused, oVirt sets
> a disk usage threshold (so called 'high water mark') based on the occupation
> of the device, and automatically extends the image once the threshold
> is reached or exceeded.
>
> In order to detect the crossing of the threshold, oVirt has no choice but
> aggressively polling the QEMU monitor using the query-blockstats command.
> This lead to unnecessary system load, and is made even worse under scale:
> deployments with hundreds of VMs are no longer rare.
>
> To fix this, this patch adds:
> * A new monitor command `block-set-write-threshold', to set a mark for
> a given block device.
> * A new event `BLOCK_WRITE_THRESHOLD', to report if a block device
> usage exceeds the threshold.
> * A new `write_threshold' field into the `BlockDeviceInfo' structure,
> to report the configured threshold.
>
> This will allow the managing application to use smarter and more
> efficient monitoring, greatly reducing the need of polling.
>
> Signed-off-by: Francesco Romani <address@hidden>
> Reviewed-by: Eric Blake <address@hidden>
> ---
> block/Makefile.objs | 1 +
> block/qapi.c | 3 +
> block/write-threshold.c | 125
> ++++++++++++++++++++++++++++++++++++++++
> include/block/block_int.h | 4 ++
> include/block/write-threshold.h | 64 ++++++++++++++++++++
> qapi/block-core.json | 51 +++++++++++++++-
> qmp-commands.hx | 32 ++++++++++
> tests/Makefile | 3 +
> tests/test-write-threshold.c | 119 ++++++++++++++++++++++++++++++++++++++
> 9 files changed, 401 insertions(+), 1 deletion(-)
> create mode 100644 block/write-threshold.c
> create mode 100644 include/block/write-threshold.h
> create mode 100644 tests/test-write-threshold.c
Thanks, applied to my block branch:
https://github.com/stefanha/qemu/tree/block
Stefan
pgpVqsB9R1g2o.pgp
Description: PGP signature