Polling and em0

[Michael Vince]

Bill Blue wrote:

>polling(4) says that supported devices include em(4) and that polling support is turned on and off with ifconfig's 'polling' option.  But ifconfig doesn't seem to recognize that option either as a standalone request or with the initial em0 setup at boot.
>
>This is after a source cvsup (releng=6 for the frozen for 6.2 sources) yesterday and buildworld + buildkernel.  em support is compiled in the kernel rather than loaded.  Mobo is a Supermicro P4SCT-0 with Intel 875 chipset.
>
>Is this a known issue that I haven't found references to, or perhaps something related to my specific configuration?
>
>FreeBSD v2.netoldies.com 6.2-PRERELEASE FreeBSD 6.2-PRERELEASE #0: Fri Sep 15 15:14:07 PDT 2006     root at v2.netoldies.com:/usr/obj/usr/src/sys/V2KERNEL  i386
>
>Thanks
>
>--Bill
>
>  
>
Since 6.1 I have stopped using polling as a regular kernel seems to give 
good performance as compared to polling mode.
In fact I used to get anything between 55-75megs/sec on 6.1 with regular 
cables but since upgraded to cat6 quality Ethernet cable I get 
practically full gigabit speed with no polling.
Close to 97megs/sec is the performance I get out of my Dells with the em 
driver, and apparently the new em driver in 6-stable 6.2 is even faster.

em(4) Dell to em(4) Dell
dell1# cat /dev/zero | dd bs=1m | nc dell2 3000
^C0+18456 records in
0+18455 records out
1209466880 bytes transferred in 12.459299 secs (97,073,429 bytes/sec)

Mike