linux/net
jamal d5b8aa1d24 net_sched: fix dequeuer fairness
Results on dummy device can be seen in my netconf 2011
slides. These results are for a 10Gige IXGBE intel
nic - on another i5 machine, very similar specs to
the one used in the netconf2011 results.
It turns out - this is a hell lot worse than dummy
and so this patch is even more beneficial for 10G.

Test setup:
----------

System under test sending packets out.
Additional box connected directly dropping packets.
Installed prio qdisc on the eth device and default
netdev default length of 1000 used as is.
The 3 prio bands each were set to 100 (didnt factor in
the results).

5 packet runs were made and the middle 3 picked.

results
-------

The "cpu" column indicates the which cpu the sample
was taken on,
The "Pkt runx" carries the number of packets a cpu
dequeued when forced to be in the "dequeuer" role.
The "avg" for each run is the number of times each
cpu should be a "dequeuer" if the system was fair.

3.0-rc4      (plain)
cpu         Pkt run1        Pkt run2        Pkt run3
================================================
cpu0        21853354        21598183        22199900
cpu1          431058          473476          393159
cpu2          481975          477529          458466
cpu3        23261406        23412299        22894315
avg         11506948        11490372        11486460

3.0-rc4 with patch and default weight 64
cpu 	     Pkt run1        Pkt run2        Pkt run3
================================================
cpu0        13205312        13109359        13132333
cpu1        10189914        10159127        10122270
cpu2        10213871        10124367        10168722
cpu3        13165760        13164767        13096705
avg         11693714        11639405        11630008

As you can see the system is still not perfect but
is a lot better than what it was before...

At the moment we use the old backlog weight, weight_p
which is 64 packets. It seems to be reasonably fine
with that value.
The system could be made more fair if we reduce the
weight_p (as per my presentation), but we are going
to affect the shared backlog weight. Unless deemed
necessary, I think the default value is fine. If not
we could add yet another knob.

Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2011-06-27 00:14:10 -07:00
..
9p Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband 2011-05-26 12:13:57 -07:00
802 snap: remove one synchronize_net() 2011-05-23 16:29:24 -04:00
8021q Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2011-06-20 22:29:08 -07:00
appletalk appletalk: Fix OOPS in atalk_release(). 2011-03-31 18:59:10 -07:00
atm net: Remove casts of void * 2011-06-16 23:19:27 -04:00
ax25 ax25: Fix set-but-unused variable. 2011-04-17 00:48:31 -07:00
batman-adv Merge branch 'batman-adv/next' of git://git.open-mesh.org/ecsv/linux-merge 2011-06-20 12:59:37 -07:00
bluetooth Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next-2.6 into for-davem 2011-06-24 15:25:51 -04:00
bridge Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2011-06-20 22:29:08 -07:00
caif Remove redundant linux/version.h includes from net/ 2011-06-21 16:03:17 -07:00
can net/can: use printk_ratelimited() instead of printk_ratelimit() 2011-06-17 00:03:03 -04:00
ceph Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2011-06-20 22:29:08 -07:00
core ip: introduce ip_is_fragment helper inline function 2011-06-21 20:33:34 -07:00
dcb dcb: use nlmsg_free() instead of kfree() 2011-06-23 03:14:42 -07:00
dccp ipv4: Make caller provide flowi4 key to inet_csk_route_req(). 2011-05-18 18:32:03 -04:00
decnet net: Remove casts of void * 2011-06-16 23:19:27 -04:00
dns_resolver
dsa Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2011-05-05 14:59:02 -07:00
econet econet: Fix set-but-unused variable. 2011-04-17 00:15:22 -07:00
ethernet
ieee802154 ieee802154: Don't leak memory in ieee802154_nl_fill_phy 2011-06-13 18:03:22 -04:00
ipv4 ip: introduce ip_is_fragment helper inline function 2011-06-21 20:33:34 -07:00
ipv6 Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2011-06-20 22:29:08 -07:00
ipx
irda Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2011-06-20 22:29:08 -07:00
iucv [S390] irq: merge irq.c and s390_ext.c 2011-05-26 09:48:24 +02:00
key net: Remove casts of void * 2011-06-16 23:19:27 -04:00
l2tp Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2011-06-20 22:29:08 -07:00
lapb
llc llc: Fix length check in llc_fixup_skb(). 2011-04-11 18:59:05 -07:00
mac80211 Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2011-06-20 22:29:08 -07:00
netfilter ip: introduce ip_is_fragment helper inline function 2011-06-21 20:33:34 -07:00
netlabel net: Remove casts of void * 2011-06-16 23:19:27 -04:00
netlink Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next-2.6 into for-davem 2011-06-24 15:25:51 -04:00
netrom NET: AX.25, NETROM, ROSE: Remove SOCK_DEBUG calls 2011-04-14 00:20:07 -07:00
packet Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2011-06-20 22:29:08 -07:00
phonet rtnetlink: Compute and store minimum ifinfo dump size 2011-06-09 20:38:07 -07:00
rds net/rds: use prink_ratelimited() instead of printk_ratelimit() 2011-06-17 00:03:03 -04:00
rfkill net: rfkill: add generic gpio rfkill driver 2011-05-19 13:53:54 -04:00
rose NET: AX.25, NETROM, ROSE: Remove SOCK_DEBUG calls 2011-04-14 00:20:07 -07:00
rxrpc rxrpc: Fix set but unused variable 'usage' in rxrpc_get_transport() 2011-05-19 18:51:50 -04:00
sched net_sched: fix dequeuer fairness 2011-06-27 00:14:10 -07:00
sctp net: Remove casts of void * 2011-06-16 23:19:27 -04:00
sunrpc Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2011-06-20 22:29:08 -07:00
tipc tipc: Optimize creation of connection protocol messages 2011-06-24 16:18:18 -04:00
unix net: convert %p usage to %pK 2011-05-24 01:13:12 -04:00
wanrouter Fix common misspellings 2011-03-31 11:26:23 -03:00
wimax
wireless nl80211: use netlink consistent dump feature for BSS dumps 2011-06-22 16:09:47 -04:00
x25 Fix common misspellings 2011-03-31 11:26:23 -03:00
xfrm Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2011-06-20 22:29:08 -07:00
compat.c net: Add sendmmsg socket system call 2011-05-05 11:10:14 -07:00
Kconfig bpf: depends on MODULES 2011-04-29 10:20:53 -07:00
Makefile
nonet.c
socket.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6 2011-05-20 13:43:21 -07:00
sysctl_net.c