Re: [PATCH 2/2] virtio-scsi: reset virtqueue affinity when doing cpu hotplug
Il 16/01/2013 04:55, Wanlong Gao ha scritto: Add hot cpu notifier to reset the request virtqueue affinity when doing cpu hotplug. You need to be careful to get_online_cpus() and put_online_cpus() here, so CPUs can't go up and down in the middle of operations. In particular, get_online_cpus()/put_online_cpus() around calls to virtscsi_set_affinity() (except within notifiers). Yes, I'll take care of this, thank you. I squashed patch 1 (plus changes to get/put_online_cpus) in my multiqueue series, and applied this one as a separate patch. Paolo -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH 2/2] virtio-scsi: reset virtqueue affinity when doing cpu hotplug
Add hot cpu notifier to reset the request virtqueue affinity
when doing cpu hotplug.
Signed-off-by: Wanlong Gao gaowanl...@cn.fujitsu.com
---
drivers/scsi/virtio_scsi.c | 30 ++
1 file changed, 30 insertions(+)
diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index 16b0ef2..a3b5f12 100644
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -20,6 +20,7 @@
#include linux/virtio_ids.h
#include linux/virtio_config.h
#include linux/virtio_scsi.h
+#include linux/cpu.h
#include scsi/scsi_host.h
#include scsi/scsi_device.h
#include scsi/scsi_cmnd.h
@@ -109,6 +110,9 @@ struct virtio_scsi {
/* Does the affinity hint is set for virtqueues? */
bool affinity_hint_set;
+ /* CPU hotplug notifier */
+ struct notifier_block nb;
+
struct virtio_scsi_vq ctrl_vq;
struct virtio_scsi_vq event_vq;
struct virtio_scsi_vq req_vqs[];
@@ -738,6 +742,23 @@ static void virtscsi_set_affinity(struct virtio_scsi
*vscsi, bool affinity)
}
}
+static int virtscsi_cpu_callback(struct notifier_block *nfb,
+unsigned long action, void *hcpu)
+{
+ struct virtio_scsi *vscsi = container_of(nfb, struct virtio_scsi, nb);
+ switch(action) {
+ case CPU_ONLINE:
+ case CPU_ONLINE_FROZEN:
+ case CPU_DEAD:
+ case CPU_DEAD_FROZEN:
+ virtscsi_set_affinity(vscsi, true);
+ break;
+ default:
+ break;
+ }
+ return NOTIFY_OK;
+}
+
static void virtscsi_init_vq(struct virtio_scsi_vq *virtscsi_vq,
struct virtqueue *vq)
{
@@ -888,6 +909,13 @@ static int __devinit virtscsi_probe(struct virtio_device
*vdev)
if (err)
goto virtscsi_init_failed;
+ vscsi-nb.notifier_call = virtscsi_cpu_callback;
+ err = register_hotcpu_notifier(vscsi-nb);
+ if (err) {
+ pr_err(virtio_scsi: registering cpu notifier failed\n);
+ goto scsi_add_host_failed;
+ }
+
cmd_per_lun = virtscsi_config_get(vdev, cmd_per_lun) ?: 1;
shost-cmd_per_lun = min_t(u32, cmd_per_lun, shost-can_queue);
shost-max_sectors = virtscsi_config_get(vdev, max_sectors) ?: 0x;
@@ -925,6 +953,8 @@ static void __devexit virtscsi_remove(struct virtio_device
*vdev)
scsi_remove_host(shost);
+ unregister_hotcpu_notifier(vscsi-nb);
+
virtscsi_remove_vqs(vdev);
scsi_host_put(shost);
}
--
1.8.1
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Re: [PATCH 2/2] virtio-scsi: reset virtqueue affinity when doing cpu hotplug
Wanlong Gao gaowanl...@cn.fujitsu.com writes:
Add hot cpu notifier to reset the request virtqueue affinity
when doing cpu hotplug.
You need to be careful to get_online_cpus() and put_online_cpus() here,
so CPUs can't go up and down in the middle of operations.
In particular, get_online_cpus()/put_online_cpus() around calls to
virtscsi_set_affinity() (except within notifiers).
+static int virtscsi_cpu_callback(struct notifier_block *nfb,
+ unsigned long action, void *hcpu)
+{
+ struct virtio_scsi *vscsi = container_of(nfb, struct virtio_scsi, nb);
+ switch(action) {
+ case CPU_ONLINE:
+ case CPU_ONLINE_FROZEN:
+ case CPU_DEAD:
+ case CPU_DEAD_FROZEN:
+ virtscsi_set_affinity(vscsi, true);
+ break;
+ default:
+ break;
+ }
+ return NOTIFY_OK;
+}
You probably want to remove affinities *before* the CPU goes down, and
restore it after the CPU comes up.
So, how about:
switch (action ~CPU_TASKS_FROZEN) {
case CPU_ONLINE:
case CPU_DOWN_FAILED:
virtscsi_set_affinity(vscsi, true, -1);
break;
case CPU_DOWN_PREPARE:
virtscsi_set_affinity(vscsi, true, (unsigned long)hcpu);
break;
}
The extra argument to virtscsi_set_affinity() is to tell it to ignore a
cpu which seems online (because it's going down).
static void virtscsi_init_vq(struct virtio_scsi_vq *virtscsi_vq,
struct virtqueue *vq)
{
@@ -888,6 +909,13 @@ static int __devinit virtscsi_probe(struct virtio_device
*vdev)
if (err)
goto virtscsi_init_failed;
+ vscsi-nb.notifier_call = virtscsi_cpu_callback;
+ err = register_hotcpu_notifier(vscsi-nb);
+ if (err) {
+ pr_err(virtio_scsi: registering cpu notifier failed\n);
+ goto scsi_add_host_failed;
+ }
+
You have to clean this up if scsi_add_host() fails, I think.
Cheers,
Rusty.
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Re: [PATCH 2/2] virtio-scsi: reset virtqueue affinity when doing cpu hotplug
On 01/16/2013 11:31 AM, Rusty Russell wrote:
Wanlong Gao gaowanl...@cn.fujitsu.com writes:
Add hot cpu notifier to reset the request virtqueue affinity
when doing cpu hotplug.
You need to be careful to get_online_cpus() and put_online_cpus() here,
so CPUs can't go up and down in the middle of operations.
In particular, get_online_cpus()/put_online_cpus() around calls to
virtscsi_set_affinity() (except within notifiers).
Yes, I'll take care of this, thank you.
+static int virtscsi_cpu_callback(struct notifier_block *nfb,
+ unsigned long action, void *hcpu)
+{
+struct virtio_scsi *vscsi = container_of(nfb, struct virtio_scsi, nb);
+switch(action) {
+case CPU_ONLINE:
+case CPU_ONLINE_FROZEN:
+case CPU_DEAD:
+case CPU_DEAD_FROZEN:
+virtscsi_set_affinity(vscsi, true);
+break;
+default:
+break;
+}
+return NOTIFY_OK;
+}
You probably want to remove affinities *before* the CPU goes down, and
restore it after the CPU comes up.
So, how about:
switch (action ~CPU_TASKS_FROZEN) {
case CPU_ONLINE:
case CPU_DOWN_FAILED:
virtscsi_set_affinity(vscsi, true, -1);
break;
case CPU_DOWN_PREPARE:
virtscsi_set_affinity(vscsi, true, (unsigned long)hcpu);
break;
}
The extra argument to virtscsi_set_affinity() is to tell it to ignore a
cpu which seems online (because it's going down).
OK, thank you very much for teaching this.
static void virtscsi_init_vq(struct virtio_scsi_vq *virtscsi_vq,
struct virtqueue *vq)
{
@@ -888,6 +909,13 @@ static int __devinit virtscsi_probe(struct
virtio_device *vdev)
if (err)
goto virtscsi_init_failed;
+vscsi-nb.notifier_call = virtscsi_cpu_callback;
+err = register_hotcpu_notifier(vscsi-nb);
+if (err) {
+pr_err(virtio_scsi: registering cpu notifier failed\n);
+goto scsi_add_host_failed;
+}
+
You have to clean this up if scsi_add_host() fails, I think.
Yeah, will do, thank you very much.
Regards,
Wanlong Gao
Cheers,
Rusty.
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