diff options
| author | Denis Plotnikov <dplotnikov@virtuozzo.com> | 2020-02-14 10:46:48 +0300 |
|---|---|---|
| committer | Stefan Hajnoczi <stefanha@redhat.com> | 2020-02-22 08:26:47 +0000 |
| commit | c9b7d9ec21dfca716f0bb3b68dee75660d86629c (patch) | |
| tree | a1dd32e40939607157457ed2dec0d16f5e4ff295 /hw | |
| parent | 9ac5df20f51fabcba0d902025df4bd7ea987c158 (diff) | |
virtio: increase virtqueue size for virtio-scsi and virtio-blk
The goal is to reduce the amount of requests issued by a guest on
1M reads/writes. This rises the performance up to 4% on that kind of
disk access pattern.
The maximum chunk size to be used for the guest disk accessing is
limited with seg_max parameter, which represents the max amount of
pices in the scatter-geather list in one guest disk request.
Since seg_max is virqueue_size dependent, increasing the virtqueue
size increases seg_max, which, in turn, increases the maximum size
of data to be read/write from a guest disk.
More details in the original problem statment:
https://lists.gnu.org/archive/html/qemu-devel/2017-12/msg03721.html
Suggested-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Denis Plotnikov <dplotnikov@virtuozzo.com>
Message-id: 20200214074648.958-1-dplotnikov@virtuozzo.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'hw')
| -rw-r--r-- | hw/block/virtio-blk.c | 2 | ||||
| -rw-r--r-- | hw/core/machine.c | 2 | ||||
| -rw-r--r-- | hw/scsi/virtio-scsi.c | 2 |
3 files changed, 4 insertions, 2 deletions
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c index 09f46ed85f..142863a3b2 100644 --- a/hw/block/virtio-blk.c +++ b/hw/block/virtio-blk.c @@ -1272,7 +1272,7 @@ static Property virtio_blk_properties[] = { DEFINE_PROP_BIT("request-merging", VirtIOBlock, conf.request_merging, 0, true), DEFINE_PROP_UINT16("num-queues", VirtIOBlock, conf.num_queues, 1), - DEFINE_PROP_UINT16("queue-size", VirtIOBlock, conf.queue_size, 128), + DEFINE_PROP_UINT16("queue-size", VirtIOBlock, conf.queue_size, 256), DEFINE_PROP_BOOL("seg-max-adjust", VirtIOBlock, conf.seg_max_adjust, true), DEFINE_PROP_LINK("iothread", VirtIOBlock, conf.iothread, TYPE_IOTHREAD, IOThread *), diff --git a/hw/core/machine.c b/hw/core/machine.c index 84812a1d1c..ce403ccea9 100644 --- a/hw/core/machine.c +++ b/hw/core/machine.c @@ -28,6 +28,8 @@ #include "hw/mem/nvdimm.h" GlobalProperty hw_compat_4_2[] = { + { "virtio-blk-device", "queue-size", "128"}, + { "virtio-scsi-device", "virtqueue_size", "128"}, { "virtio-blk-device", "x-enable-wce-if-config-wce", "off" }, { "virtio-blk-device", "seg-max-adjust", "off"}, { "virtio-scsi-device", "seg_max_adjust", "off"}, diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c index 3b61563609..472bbd233b 100644 --- a/hw/scsi/virtio-scsi.c +++ b/hw/scsi/virtio-scsi.c @@ -965,7 +965,7 @@ static void virtio_scsi_device_unrealize(DeviceState *dev, Error **errp) static Property virtio_scsi_properties[] = { DEFINE_PROP_UINT32("num_queues", VirtIOSCSI, parent_obj.conf.num_queues, 1), DEFINE_PROP_UINT32("virtqueue_size", VirtIOSCSI, - parent_obj.conf.virtqueue_size, 128), + parent_obj.conf.virtqueue_size, 256), DEFINE_PROP_BOOL("seg_max_adjust", VirtIOSCSI, parent_obj.conf.seg_max_adjust, true), DEFINE_PROP_UINT32("max_sectors", VirtIOSCSI, parent_obj.conf.max_sectors, |