| Message ID | 1395880676-4472-1-git-send-email-dborkman@redhat.com |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
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. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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... -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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;
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(-)