Bump default from 8 to 64 blocks. Using 8 by default leads to requests being splitted on qemu, which slows down boot.
Some (temporary) debug logging added showed that almost all requests on a standard fedora install are less than 64 blocks, so that should bring us back to 1.15 performance levels.
Signed-off-by: Gerd Hoffmann kraxel@redhat.com --- src/hw/virtio-blk.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/hw/virtio-blk.c b/src/hw/virtio-blk.c index 929ba8873dc0..9b4a05a4c424 100644 --- a/src/hw/virtio-blk.c +++ b/src/hw/virtio-blk.c @@ -95,7 +95,7 @@ virtio_blk_op(struct disk_op_s *op, int write) blk_num_max = (u16)max_io_size / vdrive->drive.blksize; else /* default blk_num_max if hardware doesnot advise a proper value */ - blk_num_max = 8; + blk_num_max = 64;
if (op->count <= blk_num_max) { virtio_blk_op_one_segment(vdrive, write, sg);
On Thu, Jul 07, 2022 at 12:06:16PM +0200, Gerd Hoffmann wrote:
Bump default from 8 to 64 blocks. Using 8 by default leads to requests being splitted on qemu, which slows down boot.
Some (temporary) debug logging added showed that almost all requests on a standard fedora install are less than 64 blocks, so that should bring us back to 1.15 performance levels.
Thanks. Looks fine to me.
-Kevin
On Thu, Jul 07, 2022 at 11:13:52AM -0400, Kevin O'Connor wrote:
On Thu, Jul 07, 2022 at 12:06:16PM +0200, Gerd Hoffmann wrote:
Bump default from 8 to 64 blocks. Using 8 by default leads to requests being splitted on qemu, which slows down boot.
Some (temporary) debug logging added showed that almost all requests on a standard fedora install are less than 64 blocks, so that should bring us back to 1.15 performance levels.
Thanks. Looks fine to me.
Pushed now.
take care, Gerd
-
Gerd Hoffmann -
Kevin O'Connor