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Increase the (arbitrary) limit for the number of packets per tick

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from 1k to 20k The previous value was good 10 years ago, but not
anymore now.

More importantly, lots of good surprises:
polling is incredibly effective under virtualization, and not only
prevents livelock but also saves most of the VM exit overhead in
receive mode.

Using polling, a FreeBSD instance under qemu-kvm remains perfectly
responsive even when bombed with 10 Mpps over an emulated e1000,
and happily processes 1.7 Mpps through ipfw.

Note that some incompatibilities still remain: e.g. polling is not
(yet) compatible with netmap, and seems to freeze the guest when
kern.polling.idle_poll=1

MFC after:	3 days
This commit is contained in:
Luigi Rizzo 2013-05-22 16:32:18 +00:00
parent 83b375ea16
commit 4b62214f4a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=250911
1 changed files with 1 additions and 2 deletions
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3
sys/kern/kern_poll.c
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@ -87,12 +87,11 @@ static struct mtx poll_mtx;
* The following constraints hold
*
* 1 <= poll_each_burst <= poll_burst <= poll_burst_max
* 0 <= poll_each_burst
* MIN_POLL_BURST_MAX <= poll_burst_max <= MAX_POLL_BURST_MAX
*/
#define MIN_POLL_BURST_MAX 10
#define MAX_POLL_BURST_MAX 1000
#define MAX_POLL_BURST_MAX 20000
static uint32_t poll_burst = 5;
static uint32_t poll_burst_max = 150; /* good for 100Mbit net and HZ=1000 */