Don't arm tx hrtimer with a constant 500us each transmit

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

drivers/net/virtio_net.c again:

Quoted 3 lines

drivers/net/virtio_net.c +0 -0

@@ -406,10 +405,10 @@ again:

Hmm, while I agree in general with the patch, I fail to find the proper version of virtio_net where this patch applies. I tried kvm.git and linux-2.6.git from kernel.org. Can you give me a pointer to the repository where you work on virtio?

Christian

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

drivers/net/virtio_net.c again:

Quoted 3 lines

drivers/net/virtio_net.c +0 -0

@@ -406,10 +405,10 @@ again:

Hmm, while I agree in general with the patch, I fail to find the proper version of virtio_net where this patch applies. I tried kvm.git and linux-2.6.git from kernel.org. Can you give me a pointer to the repository where you work on virtio?

Christian

Quoted 9 lines · Christian Borntraeger

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

drivers/net/virtio_net.c again:

Quoted 3 lines

drivers/net/virtio_net.c +0 -0

@@ -406,10 +405,10 @@ again:

Hmm, while I agree in general with the patch, I fail to find the proper version of virtio_net where this patch applies. I tried kvm.git and linux-2.6.git from kernel.org. Can you give me a pointer to the

Quoted 2 lines

where you work on virtio?

Sorry for that, I added some debug prints of my one.
Here it is: *git clone git*://kvm.*qumranet*.com/home/*dor*/src/linux-2.6-nv use branch 'virtio'.

BTW: what git repository do you use?

Quoted 9 lines · Christian Borntraeger

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

drivers/net/virtio_net.c again:

Quoted 3 lines

drivers/net/virtio_net.c +0 -0

@@ -406,10 +405,10 @@ again:

Hmm, while I agree in general with the patch, I fail to find the proper version of virtio_net where this patch applies. I tried kvm.git and linux-2.6.git from kernel.org. Can you give me a pointer to the

Quoted 2 lines

where you work on virtio?

Sorry for that, I added some debug prints of my one.
Here it is: *git clone git*://kvm.*qumranet*.com/home/*dor*/src/linux-2.6-nv use branch 'virtio'.

BTW: what git repository do you use?

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

Quoted 8 lines

Quoted 7 lines · Christian Borntraeger

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

drivers/net/virtio_net.c again:

Quoted 3 lines

drivers/net/virtio_net.c +0 -0

@@ -406,10 +405,10 @@ again:

Hmm, while I agree in general with the patch, I fail to find the

proper

Quoted 2 lines

Quoted 2 lines

version of virtio_net where this patch applies. I tried kvm.git and linux-2.6.git from kernel.org. Can you give me a pointer to the

repository

Quoted 5 lines

Quoted 2 lines

where you work on virtio?

Sorry for that, I added some debug prints of my one. Here it is: *git clone git*://kvm.*qumranet*.com/home/*dor*/src/linux-2.6-nv use branch

'virtio'.

Ah, ok. I will look into that branch.

Quoted 1 line

BTW: what git repository do you use?

I use Avis git from kernel.org:
git://git.kernel.org/pub/scm/linux/kernel/git/avi/kvm

Christian

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

Quoted 8 lines

Quoted 7 lines · Christian Borntraeger

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

drivers/net/virtio_net.c again:

Quoted 3 lines

drivers/net/virtio_net.c +0 -0

@@ -406,10 +405,10 @@ again:

Hmm, while I agree in general with the patch, I fail to find the

proper

Quoted 2 lines

Quoted 2 lines

version of virtio_net where this patch applies. I tried kvm.git and linux-2.6.git from kernel.org. Can you give me a pointer to the

repository

Quoted 5 lines

Quoted 2 lines

where you work on virtio?

Sorry for that, I added some debug prints of my one. Here it is: *git clone git*://kvm.*qumranet*.com/home/*dor*/src/linux-2.6-nv use branch

'virtio'.

Ah, ok. I will look into that branch.

Quoted 1 line

BTW: what git repository do you use?

I use Avis git from kernel.org:
git://git.kernel.org/pub/scm/linux/kernel/git/avi/kvm

Christian

Quoted 10 lines · Christian Borntraeger

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

Quoted 6 lines

Quoted 5 lines · Christian Borntraeger

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

drivers/net/virtio_net.c again:

Quoted 3 lines

drivers/net/virtio_net.c +0 -0

@@ -406,10 +405,10 @@ again:

Hmm, while I agree in general with the patch, I fail to find the

proper

Quoted 2 lines

Quoted 2 lines

version of virtio_net where this patch applies. I tried kvm.git and linux-2.6.git from kernel.org. Can you give me a pointer to the

Quoted 8 lines

repository

Quoted 5 lines

Quoted 2 lines

where you work on virtio?

Sorry for that, I added some debug prints of my one. Here it is: *git clone git*://kvm.*qumranet*.com/home/*dor*/src/linux-2.6-nv use branch

'virtio'.

Quoted 11 lines · Dor Laor

Quoted 10 lines · Christian Borntraeger

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

Quoted 6 lines

Quoted 5 lines · Christian Borntraeger

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

drivers/net/virtio_net.c again:

Quoted 3 lines

drivers/net/virtio_net.c +0 -0

@@ -406,10 +405,10 @@ again:

Hmm, while I agree in general with the patch, I fail to find the

proper

Quoted 2 lines

Quoted 2 lines

version of virtio_net where this patch applies. I tried kvm.git and linux-2.6.git from kernel.org. Can you give me a pointer to the

Quoted 8 lines

Quoted 8 lines

repository

Quoted 5 lines

Quoted 2 lines

where you work on virtio?

Sorry for that, I added some debug prints of my one. Here it is: *git clone git*://kvm.*qumranet*.com/home/*dor*/src/linux-2.6-nv use branch

'virtio'.

Hi Dor,

Which userspace repo is usable with the above repo?

Thanks,
Cam

Quoted 21 lines · Cam Macdonell

Quoted 19 lines · Dor Laor

Quoted 18 lines · Christian Borntraeger

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

Quoted 6 lines

Quoted 5 lines · Christian Borntraeger

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

drivers/net/virtio_net.c again:

Quoted 3 lines

drivers/net/virtio_net.c +0 -0

@@ -406,10 +405,10 @@ again:

Hmm, while I agree in general with the patch, I fail to find the

proper

Quoted 2 lines

Quoted 2 lines

version of virtio_net where this patch applies. I tried kvm.git and linux-2.6.git from kernel.org. Can you give me a pointer to the

repository

Quoted 5 lines

Quoted 2 lines

where you work on virtio?

Sorry for that, I added some debug prints of my one. Here it is: *git clone git*://kvm.*qumranet*.com/home/*dor*/src/linux-2.6-nv use branch

'virtio'.

Quoted 7 lines

Hi Dor,

Which userspace repo is usable with the above repo?

Thanks,
Cam

git://kvm.qumranet.com/home/dor/src/kvm-nv use branch

commit 763769621d271d92204ed27552d75448587c1ac0

Author: Dor Laor <[email protected]>
Date:   Wed Dec 12 14:52:00 2007 +0200

[virtio-net][PATCH] Don't arm tx hrtimer with a constant 50us each
transmit

The current start_xmit sets 500us hrtimer to kick the host. The problem is that if another xmit happens before the timer was
fired then
the first xmit will have to wait additional 500us. This patch does not re-arm the timer if there is existing one. This will shorten the latency for tx.

Signed-off-by Dor Laor <[email protected]>

drivers/net/virtio_net.c +4 -4

index 7b051d5..8bb17d1
@@ -406,10 +405,10 @@ again:
         virtio_debug(vdebug, "%s: before calling kick %d\n",
 __FUNCTION__, __LINE__);
         vi->svq->vq_ops->kick(vi->svq);
         vi->out_num = 0;
-    } else {
-        vi->stats.hrtimer_starts++;
-        hrtimer_start(&vi->tx_timer, ktime_set(0,500000),
-                  HRTIMER_MODE_REL);
+    } else if (!hrtimer_is_queued(&vi->tx_timer)) {
+            vi->stats.hrtimer_starts++;
+            hrtimer_start(&vi->tx_timer, ktime_set(0,500000),
+                      HRTIMER_MODE_REL);
     }
     return 0;

}

commit 763769621d271d92204ed27552d75448587c1ac0

Author: Dor Laor <[email protected]>
Date:   Wed Dec 12 14:52:00 2007 +0200

[virtio-net][PATCH] Don't arm tx hrtimer with a constant 50us each
transmit

The current start_xmit sets 500us hrtimer to kick the host. The problem is that if another xmit happens before the timer was
fired then
the first xmit will have to wait additional 500us. This patch does not re-arm the timer if there is existing one. This will shorten the latency for tx.

Signed-off-by Dor Laor <[email protected]>

drivers/net/virtio_net.c +4 -4

index 7b051d5..8bb17d1
@@ -406,10 +405,10 @@ again:
         virtio_debug(vdebug, "%s: before calling kick %d\n",
 __FUNCTION__, __LINE__);
         vi->svq->vq_ops->kick(vi->svq);
         vi->out_num = 0;
-    } else {
-        vi->stats.hrtimer_starts++;
-        hrtimer_start(&vi->tx_timer, ktime_set(0,500000),
-                  HRTIMER_MODE_REL);
+    } else if (!hrtimer_is_queued(&vi->tx_timer)) {
+            vi->stats.hrtimer_starts++;
+            hrtimer_start(&vi->tx_timer, ktime_set(0,500000),
+                      HRTIMER_MODE_REL);
     }
     return 0;

}

Quoted 7 lines · On Wednesday 12 December 2007 23:54:00 Dor Laor wrote:

commit 763769621d271d92204ed27552d75448587c1ac0

Author: Dor Laor <dor.laor-atKUWr5tajBWk0Htik3J/[email protected]>
Date:   Wed Dec 12 14:52:00 2007 +0200

[virtio-net][PATCH] Don't arm tx hrtimer with a constant 50us each
transmit

Quoted 7 lines

The current start_xmit sets 500us hrtimer to kick the host. The problem is that if another xmit happens before the timer was
fired then
the first xmit will have to wait additional 500us. This patch does not re-arm the timer if there is existing one. This will shorten the latency for tx.

Hi Dor!

Yes, I pondered this when I wrote the code. On the one hand, it's a
low-probability pathological corner case, on the other, your patch reduces the number of timer reprograms in the normal case.

Quoted 7 lines · On Wednesday 12 December 2007 23:54:00 Dor Laor wrote:

commit 763769621d271d92204ed27552d75448587c1ac0

Author: Dor Laor <[email protected]>
Date:   Wed Dec 12 14:52:00 2007 +0200

[virtio-net][PATCH] Don't arm tx hrtimer with a constant 50us each
transmit

Quoted 7 lines

The current start_xmit sets 500us hrtimer to kick the host. The problem is that if another xmit happens before the timer was
fired then
the first xmit will have to wait additional 500us. This patch does not re-arm the timer if there is existing one. This will shorten the latency for tx.

Hi Dor!

Yes, I pondered this when I wrote the code. On the one hand, it's a
low-probability pathological corner case, on the other, your patch reduces the number of timer reprograms in the normal case.

Quoted 3 lines · Rusty Russell

Yes, I pondered this when I wrote the code. On the one hand, it's a
low-probability pathological corner case, on the other, your patch reduces the number of timer reprograms in the normal case.

One thing that came up in our discussions is to let the host do the timer processing instead of the guest. When tx exit mitigation is enabled, the guest bumps the queue pointer, but carefully refrains from kicking the host. The host polls the tx pointer using a timer, kicking itself periodically; if polling yields no packets it disables tx exit mitigation. This saves the guest the bother of programming the timer, which presumably requires an exit if the timer is the closest one to expiration.

[btw, this can be implemented in virtqueue rather than virtio-net, no?]

Quoted 3 lines · Rusty Russell

Yes, I pondered this when I wrote the code. On the one hand, it's a
low-probability pathological corner case, on the other, your patch reduces the number of timer reprograms in the normal case.

One thing that came up in our discussions is to let the host do the timer processing instead of the guest. When tx exit mitigation is enabled, the guest bumps the queue pointer, but carefully refrains from kicking the host. The host polls the tx pointer using a timer, kicking itself periodically; if polling yields no packets it disables tx exit mitigation. This saves the guest the bother of programming the timer, which presumably requires an exit if the timer is the closest one to expiration.

[btw, this can be implemented in virtqueue rather than virtio-net, no?]

Quoted 22 lines · Dor Laor

Quoted 21 lines · Cam Macdonell

Quoted 19 lines · Dor Laor

Quoted 18 lines · Christian Borntraeger

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

Quoted 6 lines

Quoted 5 lines · Christian Borntraeger

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

drivers/net/virtio_net.c again:

Quoted 3 lines

drivers/net/virtio_net.c +0 -0

@@ -406,10 +405,10 @@ again:

Hmm, while I agree in general with the patch, I fail to find the

proper

Quoted 2 lines

Quoted 2 lines

version of virtio_net where this patch applies. I tried kvm.git and linux-2.6.git from kernel.org. Can you give me a pointer to the

repository

Quoted 5 lines

Quoted 2 lines

where you work on virtio?

Sorry for that, I added some debug prints of my one. Here it is: *git clone git*://kvm.*qumranet*.com/home/*dor*/src/linux-2.6-nv use branch

'virtio'.

Quoted 8 lines

Quoted 7 lines

Hi Dor,

Which userspace repo is usable with the above repo?

Thanks,
Cam

git://kvm.qumranet.com/home/dor/src/kvm-nv use branch

Hi Dor,

I think you forgot a word after branch above. Also, I get the following error when I try clone the userspace repo.

cam@madhatter:~/src/KVM$ git clone
git://kvm.qumranet.com/home/dor/src/kvm-nv
Initialized empty Git repository in /home/cam/src/KVM/kvm-nv/.git/
fatal: The remote end hung up unexpectedly
fetch-pack from 'git://kvm.qumranet.com/home/dor/src/kvm-nv' failed.

Thanks,
Cam

Quoted 7 lines · On Wednesday 12 December 2007 23:54:00 Dor Laor wrote:

commit 763769621d271d92204ed27552d75448587c1ac0

Author: Dor Laor <dor.laor-atKUWr5tajBWk0Htik3J/[email protected]>
Date:   Wed Dec 12 14:52:00 2007 +0200

[virtio-net][PATCH] Don't arm tx hrtimer with a constant 50us each
transmit

Quoted 7 lines

The current start_xmit sets 500us hrtimer to kick the host. The problem is that if another xmit happens before the timer was
fired then
the first xmit will have to wait additional 500us. This patch does not re-arm the timer if there is existing one. This will shorten the latency for tx.

Hi Dor!

Yes, I pondered this when I wrote the code. On the one hand, it's a
low-probability pathological corner case, on the other, your patch reduces the number of timer reprograms in the normal case.

So I've applied it, thanks!
Rusty.

Quoted 18 lines

Signed-off-by Dor Laor <dor.laor-atKUWr5tajBWk0Htik3J/[email protected]>

drivers/net/virtio_net.c +0 -4

index 7b051d5..8bb17d1
@@ -406,10 +405,10 @@ again:
         virtio_debug(vdebug, "%s: before calling kick %d\n",
 __FUNCTION__, __LINE__);
         vi->svq->vq_ops->kick(vi->svq);
         vi->out_num = 0;
-    } else {
-        vi->stats.hrtimer_starts++;
-        hrtimer_start(&vi->tx_timer, ktime_set(0,500000),
-                  HRTIMER_MODE_REL);

Quoted 8 lines

drivers/net/virtio_net.c +4 -0

+    } else if (!hrtimer_is_queued(&vi->tx_timer)) {
+            vi->stats.hrtimer_starts++;
+            hrtimer_start(&vi->tx_timer, ktime_set(0,500000),
+                      HRTIMER_MODE_REL);
     }
     return 0;

}

Quoted 7 lines · On Wednesday 12 December 2007 23:54:00 Dor Laor wrote:

commit 763769621d271d92204ed27552d75448587c1ac0

Author: Dor Laor <[email protected]>
Date:   Wed Dec 12 14:52:00 2007 +0200

[virtio-net][PATCH] Don't arm tx hrtimer with a constant 50us each
transmit

Quoted 7 lines

The current start_xmit sets 500us hrtimer to kick the host. The problem is that if another xmit happens before the timer was
fired then
the first xmit will have to wait additional 500us. This patch does not re-arm the timer if there is existing one. This will shorten the latency for tx.

Hi Dor!

Yes, I pondered this when I wrote the code. On the one hand, it's a
low-probability pathological corner case, on the other, your patch reduces the number of timer reprograms in the normal case.

So I've applied it, thanks!
Rusty.

Quoted 18 lines

Signed-off-by Dor Laor <[email protected]>

drivers/net/virtio_net.c +0 -4

index 7b051d5..8bb17d1
@@ -406,10 +405,10 @@ again:
         virtio_debug(vdebug, "%s: before calling kick %d\n",
 __FUNCTION__, __LINE__);
         vi->svq->vq_ops->kick(vi->svq);
         vi->out_num = 0;
-    } else {
-        vi->stats.hrtimer_starts++;
-        hrtimer_start(&vi->tx_timer, ktime_set(0,500000),
-                  HRTIMER_MODE_REL);

Quoted 8 lines

drivers/net/virtio_net.c +4 -0

+    } else if (!hrtimer_is_queued(&vi->tx_timer)) {
+            vi->stats.hrtimer_starts++;
+            hrtimer_start(&vi->tx_timer, ktime_set(0,500000),
+                      HRTIMER_MODE_REL);
     }
     return 0;

}

Quoted 21 lines · Dor Laor

Quoted 20 lines · Cam Macdonell

Quoted 19 lines · Dor Laor

Quoted 18 lines · Christian Borntraeger

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

Quoted 6 lines

Quoted 5 lines · Christian Borntraeger

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

drivers/net/virtio_net.c again:

Quoted 3 lines

drivers/net/virtio_net.c +0 -0

@@ -406,10 +405,10 @@ again:

Hmm, while I agree in general with the patch, I fail to find the

proper

Quoted 2 lines

Quoted 2 lines

version of virtio_net where this patch applies. I tried kvm.git and linux-2.6.git from kernel.org. Can you give me a pointer to the

repository

Quoted 5 lines

Quoted 2 lines

where you work on virtio?

Sorry for that, I added some debug prints of my one. Here it is: *git clone git*://kvm.*qumranet*.com/home/*dor*/src/linux-2.6-nv use branch

'virtio'.

Quoted 8 lines

Quoted 7 lines

Hi Dor,

Which userspace repo is usable with the above repo?

Thanks,
Cam

git://kvm.qumranet.com/home/dor/src/kvm-nv use branch

Hi Dor,

I think you forgot a word after branch above. Also, I get the following error when I try clone the userspace repo.

cam@madhatter:~/src/KVM$ git clone 
git://kvm.qumranet.com/home/dor/src/kvm-nv
Initialized empty Git repository in /home/cam/src/KVM/kvm-nv/.git/
fatal: The remote end hung up unexpectedly
fetch-pack from 'git://kvm.qumranet.com/home/dor/src/kvm-nv' failed.

Quoted 32 lines · Cam Macdonell

Quoted 21 lines · Dor Laor

Quoted 20 lines · Cam Macdonell

Quoted 19 lines · Dor Laor

Quoted 18 lines · Christian Borntraeger

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

Quoted 6 lines

Quoted 5 lines · Christian Borntraeger

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

drivers/net/virtio_net.c again:

Quoted 3 lines

drivers/net/virtio_net.c +0 -0

@@ -406,10 +405,10 @@ again:

Hmm, while I agree in general with the patch, I fail to find the

proper

Quoted 2 lines

Quoted 2 lines

version of virtio_net where this patch applies. I tried kvm.git and linux-2.6.git from kernel.org. Can you give me a pointer to the

repository

Quoted 5 lines

Quoted 2 lines

where you work on virtio?

Sorry for that, I added some debug prints of my one. Here it is: *git clone git*://kvm.*qumranet*.com/home/*dor*/src/linux-2.6-nv use branch

'virtio'.

Quoted 8 lines

Quoted 7 lines

Hi Dor,

Which userspace repo is usable with the above repo?

Thanks,
Cam

git://kvm.qumranet.com/home/dor/src/kvm-nv use branch

Hi Dor,

Quoted 9 lines

I think you forgot a word after branch above. Also, I get the following error when I try clone the userspace repo.

cam@madhatter:~/src/KVM$ git clone 
git://kvm.qumranet.com/home/dor/src/kvm-nv
Initialized empty Git repository in /home/cam/src/KVM/kvm-nv/.git/
fatal: The remote end hung up unexpectedly
fetch-pack from 'git://kvm.qumranet.com/home/dor/src/kvm-nv' failed.

Ok, it works now, however, I'm getting an unknown symbol error when loading kvm in to kernel

cam@madhatter:~/src/KVM/dor$ sudo modprobe kvm
FATAL: Error inserting kvm 
(/lib/modules/2.6.22-14-generic/extra/kvm.ko): Unknown symbol in module, 
or unknown parameter (see dmesg)

dmesg output:

[89681.960000] kvm: Unknown symbol __fls

Quoted 47 lines · Cam Macdonell

Quoted 33 lines · Cam Macdonell

Quoted 22 lines · Dor Laor

Quoted 21 lines · Cam Macdonell

Quoted 20 lines · Dor Laor

Quoted 19 lines · Christian Borntraeger

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

Quoted 6 lines

Quoted 5 lines · Christian Borntraeger

Am Mittwoch, 12. Dezember 2007 schrieb Dor Laor:

drivers/net/virtio_net.c again:

Quoted 3 lines

drivers/net/virtio_net.c +0 -0

@@ -406,10 +405,10 @@ again:

Hmm, while I agree in general with the patch, I fail to find the

proper

Quoted 3 lines

Quoted 3 lines

version of virtio_net where this patch applies. I tried kvm.git and
linux-2.6.git from kernel.org. Can you give me a pointer to the

repository

Quoted 5 lines

Quoted 2 lines

where you work on virtio?

Sorry for that, I added some debug prints of my one. Here it is: *git clone git*://kvm.*qumranet*.com/home/*dor*/src/linux-2.6-nv use branch

'virtio'.

Quoted 8 lines

Quoted 7 lines

Hi Dor,

Which userspace repo is usable with the above repo?

Thanks,
Cam

git://kvm.qumranet.com/home/dor/src/kvm-nv use branch

Hi Dor,

Quoted 9 lines

I think you forgot a word after branch above. Also, I get the following error when I try clone the userspace repo.

cam@madhatter:~/src/KVM$ git clone 
git://kvm.qumranet.com/home/dor/src/kvm-nv
Initialized empty Git repository in /home/cam/src/KVM/kvm-nv/.git/
fatal: The remote end hung up unexpectedly
fetch-pack from 'git://kvm.qumranet.com/home/dor/src/kvm-nv' failed.

Ok, it works now, however, I'm getting an unknown symbol error when loading kvm in to kernel

Quoted 8 lines

cam@madhatter:~/src/KVM/dor$ sudo modprobe kvm
FATAL: Error inserting kvm 
(/lib/modules/2.6.22-14-generic/extra/kvm.ko): Unknown symbol in 
module, or unknown parameter (see dmesg)

dmesg output:

[89681.960000] kvm: Unknown symbol __fls

Hi Dor,

It seems this is a 32 v 64-bit issue. I'm running a 32-bit system. The asm-x86/bitops_64.h defines __fls whereas asm-x86/bitops_32.h defines fls. Simply replacing __fls with fls allows the module to load into the kernel and I am able to boot VMs with it.

I hope that helps.

Cam