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| author | Vincenzo Maffione <v.maffione@gmail.com> | 2016-01-31 11:29:05 +0100 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2016-02-06 20:44:08 +0200 |
| commit | be1fea9bc286f64c6c995bb0d7145a0b738aeddb (patch) | |
| tree | 2d826fa348b8eb71203dfb15ae4fb00aedb55edb /hw/pci-bridge | |
| parent | b796fcd1bf2978aed15748db04e054f34789e9eb (diff) | |
| download | qemu-be1fea9bc286f64c6c995bb0d7145a0b738aeddb.zip qemu-be1fea9bc286f64c6c995bb0d7145a0b738aeddb.tar.gz qemu-be1fea9bc286f64c6c995bb0d7145a0b738aeddb.tar.bz2 | |
virtio: read avail_idx from VQ only when necessary
The virtqueue_pop() implementation needs to check if the avail ring
contains some pending buffers. To perform this check, it is not
always necessary to fetch the avail_idx in the VQ memory, which is
expensive. This patch introduces a shadow variable tracking avail_idx
and modifies virtio_queue_empty() to access avail_idx in physical
memory only when necessary.
Signed-off-by: Vincenzo Maffione <v.maffione@gmail.com>
Message-Id: <b617d6459902773d9f4ab843bfaca764f5af8eda.1450218353.git.v.maffione@gmail.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'hw/pci-bridge')
0 files changed, 0 insertions, 0 deletions