From 7ef00c50cafaf356b9aef5f7c7865b405de6b2f5 Mon Sep 17 00:00:00 2001
From: Gerd Hoffmann <kraxel@redhat.com>
Date: Thu, 30 Jun 2022 17:28:40 +0200
Subject: [PATCH] virtio-blk: use larger default request size

RH-Author: Gerd Hoffmann <kraxel@redhat.com>
RH-MergeRequest: 5: virtio-blk: use larger default request size
RH-Commit: [1/1] 5b2833de23fdab9fc3c170e448e9ed07d9fb82dd (kraxel/centos-seabios)
RH-Bugzilla: 2108555
RH-Acked-by: Oliver Steffen <osteffen@redhat.com>
RH-Acked-by: Pawel Polawski <ppolawsk@redhat.com>
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

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>
(cherry picked from commit 46de2eec93bffa0706e6229c0da2919763c8eb04)
---
 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 929ba887..9b4a05a4 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);
-- 
2.31.1