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From: Dongli Zhang <dongli.zhang@oracle.com>
To: virtualization@lists.linux-foundation.org, kvm@vger.kernel.org,
	netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, mst@redhat.com,
	jasowang@redhat.com, pbonzini@redhat.com, stefanha@redhat.com,
	joe.jin@oracle.com, aruna.ramakrishna@oracle.com
Subject: [PATCH 1/1] vhost scsi: allocate vhost_scsi with GFP_NOWAIT to avoid delay
Date: Wed, 20 Jan 2021 21:03:28 -0800	[thread overview]
Message-ID: <20210121050328.7891-1-dongli.zhang@oracle.com> (raw)

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@oracle.com>
Cc: Joe Jin <joe.jin@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@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


WARNING: multiple messages have this Message-ID (diff)
From: Dongli Zhang <dongli.zhang@oracle.com>
To: virtualization@lists.linux-foundation.org, kvm@vger.kernel.org,
	netdev@vger.kernel.org
Cc: aruna.ramakrishna@oracle.com, mst@redhat.com, joe.jin@oracle.com,
	linux-kernel@vger.kernel.org, stefanha@redhat.com,
	pbonzini@redhat.com
Subject: [PATCH 1/1] vhost scsi: allocate vhost_scsi with GFP_NOWAIT to avoid delay
Date: Wed, 20 Jan 2021 21:03:28 -0800	[thread overview]
Message-ID: <20210121050328.7891-1-dongli.zhang@oracle.com> (raw)

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@oracle.com>
Cc: Joe Jin <joe.jin@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@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

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             reply	other threads:[~2021-01-21  5:08 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-21  5:03 Dongli Zhang [this message]
2021-01-21  5:03 ` [PATCH 1/1] vhost scsi: allocate vhost_scsi with GFP_NOWAIT to avoid delay Dongli Zhang
2021-01-21  9:00 ` Jason Wang
2021-01-21  9:00   ` Jason Wang
2021-01-23  8:01   ` Dongli Zhang
2021-01-23  8:01     ` Dongli Zhang

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