Dongli Zhang
2021-Jan-21 05:03 UTC
[PATCH 1/1] vhost scsi: allocate vhost_scsi with GFP_NOWAIT to avoid delay
The size of 'struct vhost_scsi' is order-10 (~2.3MB). It may take long
time
delay by kzalloc() to compact memory pages when there is a lack of
high-order pages. As a result, there is latency to create a VM (with
vhost-scsi) or to hotadd vhost-scsi-based storage.
The prior commit 595cb754983d ("vhost/scsi: use vmalloc for order-10
allocation") prefers to fallback only when really needed, while this patch
changes allocation to GFP_NOWAIT in order to avoid the delay caused by
memory page compact.
Cc: Aruna Ramakrishna <aruna.ramakrishna at oracle.com>
Cc: Joe Jin <joe.jin at oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang at oracle.com>
---
Another option is to rework by reducing the size of 'struct vhost_scsi',
e.g., by replacing inline vhost_scsi.vqs with just memory pointers while
each vhost_scsi.vqs[i] should be allocated separately. Please let me
know if that option is better.
drivers/vhost/scsi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 4ce9f00ae10e..85eaa4e883f4 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -1814,7 +1814,7 @@ static int vhost_scsi_open(struct inode *inode, struct
file *f)
struct vhost_virtqueue **vqs;
int r = -ENOMEM, i;
- vs = kzalloc(sizeof(*vs), GFP_KERNEL | __GFP_NOWARN | __GFP_RETRY_MAYFAIL);
+ vs = kzalloc(sizeof(*vs), GFP_NOWAIT | __GFP_NOWARN);
if (!vs) {
vs = vzalloc(sizeof(*vs));
if (!vs)
--
2.17.1
Jason Wang
2021-Jan-21 09:00 UTC
[PATCH 1/1] vhost scsi: allocate vhost_scsi with GFP_NOWAIT to avoid delay
On 2021/1/21 13:03, Dongli Zhang wrote:> The size of 'struct vhost_scsi' is order-10 (~2.3MB). It may take long time > delay by kzalloc() to compact memory pages when there is a lack of > high-order pages. As a result, there is latency to create a VM (with > vhost-scsi) or to hotadd vhost-scsi-based storage. > > The prior commit 595cb754983d ("vhost/scsi: use vmalloc for order-10 > allocation") prefers to fallback only when really needed, while this patch > changes allocation to GFP_NOWAIT in order to avoid the delay caused by > memory page compact. > > Cc: Aruna Ramakrishna <aruna.ramakrishna at oracle.com> > Cc: Joe Jin <joe.jin at oracle.com> > Signed-off-by: Dongli Zhang <dongli.zhang at oracle.com> > --- > Another option is to rework by reducing the size of 'struct vhost_scsi', > e.g., by replacing inline vhost_scsi.vqs with just memory pointers while > each vhost_scsi.vqs[i] should be allocated separately. Please let me > know if that option is better. > > drivers/vhost/scsi.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c > index 4ce9f00ae10e..85eaa4e883f4 100644 > --- a/drivers/vhost/scsi.c > +++ b/drivers/vhost/scsi.c > @@ -1814,7 +1814,7 @@ static int vhost_scsi_open(struct inode *inode, struct file *f) > struct vhost_virtqueue **vqs; > int r = -ENOMEM, i; > > - vs = kzalloc(sizeof(*vs), GFP_KERNEL | __GFP_NOWARN | __GFP_RETRY_MAYFAIL); > + vs = kzalloc(sizeof(*vs), GFP_NOWAIT | __GFP_NOWARN); > if (!vs) { > vs = vzalloc(sizeof(*vs)); > if (!vs)Can we use kvzalloc? Thanks