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[Qemu-devel] [PATCH v4 5/5] virtio-blk: add a knob to disable request me
From: |
Peter Lieven |
Subject: |
[Qemu-devel] [PATCH v4 5/5] virtio-blk: add a knob to disable request merging |
Date: |
Mon, 2 Feb 2015 14:52:22 +0100 |
this adds a knob to disable request merging for debugging or benchmarks if
dedired.
Signed-off-by: Peter Lieven <address@hidden>
---
hw/block/virtio-blk.c | 5 ++++-
include/hw/virtio/virtio-blk.h | 1 +
2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index d0a01a8..8c51a29 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -531,7 +531,8 @@ void virtio_blk_handle_request(VirtIOBlockReq *req,
MultiReqBuffer *mrb)
/* merge would exceed maximum number of requests or IO direction
* changes */
if (mrb->num_reqs > 0 && (mrb->num_reqs == VIRTIO_BLK_MAX_MERGE_REQS ||
- is_write != mrb->is_write)) {
+ is_write != mrb->is_write ||
+ !req->dev->conf.request_merging)) {
virtio_blk_submit_multireq(req->dev->blk, mrb);
}
@@ -950,6 +951,8 @@ static Property virtio_blk_properties[] = {
#ifdef __linux__
DEFINE_PROP_BIT("scsi", VirtIOBlock, conf.scsi, 0, true),
#endif
+ DEFINE_PROP_BIT("request-merging", VirtIOBlock, conf.request_merging, 0,
+ true),
DEFINE_PROP_BIT("x-data-plane", VirtIOBlock, conf.data_plane, 0, false),
DEFINE_PROP_END_OF_LIST(),
};
diff --git a/include/hw/virtio/virtio-blk.h b/include/hw/virtio/virtio-blk.h
index 2027a64..fc7d311 100644
--- a/include/hw/virtio/virtio-blk.h
+++ b/include/hw/virtio/virtio-blk.h
@@ -113,6 +113,7 @@ struct VirtIOBlkConf
uint32_t scsi;
uint32_t config_wce;
uint32_t data_plane;
+ uint32_t request_merging;
};
struct VirtIOBlockDataPlane;
--
1.9.1
- [Qemu-devel] [PATCH v4 0/5] this series adds the long missing multiread support to virtio-blk., Peter Lieven, 2015/02/02
- [Qemu-devel] [PATCH v4 2/5] hw/virtio-blk: add a constant for max number of merged requests, Peter Lieven, 2015/02/02
- [Qemu-devel] [PATCH v4 3/5] block-backend: expose bs->bl.max_transfer_length, Peter Lieven, 2015/02/02
- [Qemu-devel] [PATCH v4 1/5] block: add accounting for merged requests, Peter Lieven, 2015/02/02
- [Qemu-devel] [PATCH v4 4/5] virtio-blk: introduce multiread, Peter Lieven, 2015/02/02
- [Qemu-devel] [PATCH v4 5/5] virtio-blk: add a knob to disable request merging,
Peter Lieven <=
- Re: [Qemu-devel] [PATCH v4 0/5] this series adds the long missing multiread support to virtio-blk., Kevin Wolf, 2015/02/02