[Qemu-devel] [PATCH v2 2/2] block: bump coroutine pool size for drives

[Stefan Hajnoczi <stefanha@redhat.com>]

When a BlockDriverState is associated with a storage controller
DeviceState we expect guest I/O.  Use this opportunity to bump the
coroutine pool size by 64.

This patch ensures that the coroutine pool size scales with the number
of drives attached to the guest.  It should increase coroutine pool
usage (which makes qemu_coroutine_create() fast) without hogging too
much memory when fewer drives are attached.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/block.c b/block.c
index f80e2b2..c8379ca 100644
--- a/block.c
+++ b/block.c
@@ -2093,6 +2093,9 @@ int bdrv_attach_dev(BlockDriverState *bs, void *dev)
     }
     bs->dev = dev;
     bdrv_iostatus_reset(bs);
+
+    /* We're expecting I/O from the device so bump up coroutine pool size */
+    qemu_coroutine_adjust_pool_size(64);
     return 0;
 }
 
@@ -2112,6 +2115,7 @@ void bdrv_detach_dev(BlockDriverState *bs, void *dev)
     bs->dev_ops = NULL;
     bs->dev_opaque = NULL;
     bs->guest_block_size = 512;
+    qemu_coroutine_adjust_pool_size(-64);
 }
 
 /* TODO change to return DeviceState * when all users are qdevified */
-- 
1.9.3