* [PATCH net-next] net: dummy: make use of multi-queues
@ 2014-03-27 0:37 Daniel Borkmann
2014-03-27 2:51 ` Eric Dumazet
2014-03-27 2:52 ` Eric Dumazet
0 siblings, 2 replies; 4+ messages in thread
From: Daniel Borkmann @ 2014-03-27 0:37 UTC (permalink / raw)
To: davem; +Cc: netdev, Jesper Dangaard Brouer
Quite often it can be useful to just use the dummy device as a blackhole
sink for skbs, e.g. for packet sockets or pktgen tests. Therefore, make
use of multiqueues, so that we can simulate for that. trafgen mmap/TX_RING
example against dummy device with config foo: { fill(0xff, 64) } results
in the following performance improvements on an ordinary Core i7/2.80GHz
as we don't need to take a single queue/lock anymore:
Before:
Performance counter stats for 'trafgen -i foo -o du0 -n100000000' (10 runs):
160,975,944,159 instructions:k # 0.55 insns per cycle ( +- 0.09% )
293,319,390,278 cycles:k # 0.000 GHz ( +- 0.35% )
192,501,104 branch-misses:k ( +- 1.63% )
831 context-switches:k ( +- 9.18% )
7 cpu-migrations:k ( +- 7.40% )
69,382 cache-misses:k # 0.010 % of all cache refs ( +- 2.18% )
671,552,021 cache-references:k ( +- 1.29% )
22.856401569 seconds time elapsed ( +- 0.33% )
After:
Performance counter stats for 'trafgen -i foo -o du0 -n100000000' (10 runs):
138,669,108,882 instructions:k # 0.92 insns per cycle ( +- 0.02% )
151,222,621,155 cycles:k # 0.000 GHz ( +- 0.11% )
57,667,395 branch-misses:k ( +- 6.15% )
400 context-switches:k ( +- 2.73% )
6 cpu-migrations:k ( +- 7.51% )
67,414 cache-misses:k # 0.075 % of all cache refs ( +- 1.64% )
90,479,875 cache-references:k ( +- 0.75% )
12.080331543 seconds time elapsed ( +- 0.13% )
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
---
drivers/net/dummy.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/net/dummy.c b/drivers/net/dummy.c
index 0932ffb..b3f78a9 100644
--- a/drivers/net/dummy.c
+++ b/drivers/net/dummy.c
@@ -35,6 +35,7 @@
#include <linux/init.h>
#include <linux/moduleparam.h>
#include <linux/rtnetlink.h>
+#include <linux/cpumask.h>
#include <net/rtnetlink.h>
#include <linux/u64_stats_sync.h>
@@ -162,9 +163,10 @@ MODULE_PARM_DESC(numdummies, "Number of dummy pseudo devices");
static int __init dummy_init_one(void)
{
struct net_device *dev_dummy;
+ unsigned int numqueues = min(num_possible_cpus(), 32U);
int err;
- dev_dummy = alloc_netdev(0, "dummy%d", dummy_setup);
+ dev_dummy = alloc_netdev_mq(0, "dummy%d", dummy_setup, numqueues);
if (!dev_dummy)
return -ENOMEM;
--
1.7.11.7
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH net-next] net: dummy: make use of multi-queues
2014-03-27 0:37 [PATCH net-next] net: dummy: make use of multi-queues Daniel Borkmann
@ 2014-03-27 2:51 ` Eric Dumazet
2014-03-27 9:48 ` Daniel Borkmann
2014-03-27 2:52 ` Eric Dumazet
1 sibling, 1 reply; 4+ messages in thread
From: Eric Dumazet @ 2014-03-27 2:51 UTC (permalink / raw)
To: Daniel Borkmann; +Cc: davem, netdev, Jesper Dangaard Brouer
On Thu, 2014-03-27 at 01:37 +0100, Daniel Borkmann wrote:
> Quite often it can be useful to just use the dummy device as a blackhole
> sink for skbs, e.g. for packet sockets or pktgen tests. Therefore, make
> use of multiqueues, so that we can simulate for that. trafgen mmap/TX_RING
> example against dummy device with config foo: { fill(0xff, 64) } results
> in the following performance improvements on an ordinary Core i7/2.80GHz
> as we don't need to take a single queue/lock anymore:
>
> Before:
>
> Performance counter stats for 'trafgen -i foo -o du0 -n100000000' (10 runs):
>
> 160,975,944,159 instructions:k # 0.55 insns per cycle ( +- 0.09% )
> 293,319,390,278 cycles:k # 0.000 GHz ( +- 0.35% )
> 192,501,104 branch-misses:k ( +- 1.63% )
> 831 context-switches:k ( +- 9.18% )
> 7 cpu-migrations:k ( +- 7.40% )
> 69,382 cache-misses:k # 0.010 % of all cache refs ( +- 2.18% )
> 671,552,021 cache-references:k ( +- 1.29% )
>
> 22.856401569 seconds time elapsed ( +- 0.33% )
>
> After:
>
> Performance counter stats for 'trafgen -i foo -o du0 -n100000000' (10 runs):
>
> 138,669,108,882 instructions:k # 0.92 insns per cycle ( +- 0.02% )
> 151,222,621,155 cycles:k # 0.000 GHz ( +- 0.11% )
> 57,667,395 branch-misses:k ( +- 6.15% )
> 400 context-switches:k ( +- 2.73% )
> 6 cpu-migrations:k ( +- 7.51% )
> 67,414 cache-misses:k # 0.075 % of all cache refs ( +- 1.64% )
> 90,479,875 cache-references:k ( +- 0.75% )
>
> 12.080331543 seconds time elapsed ( +- 0.13% )
Its a LLTX device, so it looks there is no bottleneck in this driver,
but in the caller ;)
If you need many channels, you can setup as many dummy devices you want.
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH net-next] net: dummy: make use of multi-queues
2014-03-27 2:51 ` Eric Dumazet
@ 2014-03-27 9:48 ` Daniel Borkmann
0 siblings, 0 replies; 4+ messages in thread
From: Daniel Borkmann @ 2014-03-27 9:48 UTC (permalink / raw)
To: Eric Dumazet; +Cc: davem, netdev, Jesper Dangaard Brouer
On 03/27/2014 03:51 AM, Eric Dumazet wrote:
> On Thu, 2014-03-27 at 01:37 +0100, Daniel Borkmann wrote:
>> Quite often it can be useful to just use the dummy device as a blackhole
>> sink for skbs, e.g. for packet sockets or pktgen tests. Therefore, make
>> use of multiqueues, so that we can simulate for that. trafgen mmap/TX_RING
>> example against dummy device with config foo: { fill(0xff, 64) } results
>> in the following performance improvements on an ordinary Core i7/2.80GHz
>> as we don't need to take a single queue/lock anymore:
>>
>> Before:
>>
>> Performance counter stats for 'trafgen -i foo -o du0 -n100000000' (10 runs):
>>
>> 160,975,944,159 instructions:k # 0.55 insns per cycle ( +- 0.09% )
>> 293,319,390,278 cycles:k # 0.000 GHz ( +- 0.35% )
>> 192,501,104 branch-misses:k ( +- 1.63% )
>> 831 context-switches:k ( +- 9.18% )
>> 7 cpu-migrations:k ( +- 7.40% )
>> 69,382 cache-misses:k # 0.010 % of all cache refs ( +- 2.18% )
>> 671,552,021 cache-references:k ( +- 1.29% )
>>
>> 22.856401569 seconds time elapsed ( +- 0.33% )
>>
>> After:
>>
>> Performance counter stats for 'trafgen -i foo -o du0 -n100000000' (10 runs):
>>
>> 138,669,108,882 instructions:k # 0.92 insns per cycle ( +- 0.02% )
>> 151,222,621,155 cycles:k # 0.000 GHz ( +- 0.11% )
>> 57,667,395 branch-misses:k ( +- 6.15% )
>> 400 context-switches:k ( +- 2.73% )
>> 6 cpu-migrations:k ( +- 7.51% )
>> 67,414 cache-misses:k # 0.075 % of all cache refs ( +- 1.64% )
>> 90,479,875 cache-references:k ( +- 0.75% )
>>
>> 12.080331543 seconds time elapsed ( +- 0.13% )
>
>
>
> Its a LLTX device, so it looks there is no bottleneck in this driver,
> but in the caller ;)
Ohh, I see the issue, thanks for pointing this out Eric.
I'll fix this up differently. ;-)
> If you need many channels, you can setup as many dummy devices you want.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH net-next] net: dummy: make use of multi-queues
2014-03-27 0:37 [PATCH net-next] net: dummy: make use of multi-queues Daniel Borkmann
2014-03-27 2:51 ` Eric Dumazet
@ 2014-03-27 2:52 ` Eric Dumazet
1 sibling, 0 replies; 4+ messages in thread
From: Eric Dumazet @ 2014-03-27 2:52 UTC (permalink / raw)
To: Daniel Borkmann; +Cc: davem, netdev, Jesper Dangaard Brouer
On Thu, 2014-03-27 at 01:37 +0100, Daniel Borkmann wrote:
> Quite often it can be useful to just use the dummy device as a blackhole
> sink for skbs, e.g. for packet sockets or pktgen tests. Therefore, make
> use of multiqueues, so that we can simulate for that. trafgen mmap/TX_RING
> example against dummy device with config foo: { fill(0xff, 64) } results
> in the following performance improvements on an ordinary Core i7/2.80GHz
> as we don't need to take a single queue/lock anymore:
btw, this driver has percpu stats, so memory needs will explode with
your patch...
^ permalink raw reply [flat|nested] 4+ messages in thread
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2014-03-27 2:52 ` Eric Dumazet
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