[Intel-wired-lan] [PATCH] ixgbe: Limit lowest interrupt rate for adaptive interrupt moderation to 12K
Singh, Krishneil K
krishneil.k.singh at intel.com
Thu Sep 10 19:49:40 UTC 2015
From: Intel-wired-lan [mailto:intel-wired-lan-bounces at lists.osuosl.org] On Behalf Of Jeff Kirsher
Sent: Wednesday, September 2, 2015 3:07 AM
To: Alexander Duyck <alexander.duyck at gmail.com>
Cc: netdev at vger.kernel.org; intel-wired-lan at lists.osuosl.org
Subject: Re: [Intel-wired-lan] [PATCH] ixgbe: Limit lowest interrupt rate for adaptive interrupt moderation to 12K
On Tue, 2015-09-01 at 18:49 -0700, Alexander Duyck wrote:
> On 07/30/2015 03:19 PM, Alexander Duyck wrote:
> > This patch updates the lowest limit for adaptive interrupt interrupt
> > moderation to roughly 12K interrupts per second.
> > The way I came about reaching 12K as the desired interrupt rate is
> > testing with UDP flows. Specifically I had a simple test that ran a
> > netperf UDP_STREAM test at varying sizes. What I found was as the
> > sizes increased the performance fell steadily behind until we were
> > able to receive at ~4Gb/s with a message size of 65507. A bit of
> > found that we were dropping packets for the socket in the network
> > and looking at things further what I found was I could solve it by
> > the interrupt rate, or increasing the rmem_default/rmem_max. What I
> found was
> > that when the interrupt coalescing resulted in more data being
> > per interrupt than could be stored in the socket buffer we started
> > packets and the performance dropped. So I reached 12K based on the
> > following math.
> > rmem_default = 212992
> > skb->truesize = 2994
> > 212992 / 2994 = 71.14 packets to fill the buffer
> > packet rate at 1514 packet size is 812744pps
> > 71.14 / 812744 = 87.9us to fill socket buffer
> > >From there it was just a matter of choosing the interrupt rate and
> > providing a bit of wiggle room which is why I decided to go with 12K
> > interrupts per second as that uses a value of 84us.
> > The data below is based on VM to VM over a direct assigned ixgbe
> > The test run was:
> > netperf -H <ip> -t UDP_STREAM"
> > Socket Message Elapsed Messages CPU
> > Size Size Time Okay Errors Throughput Util
> > bytes bytes secs # # 10^6bits/sec % SS
> > Before:
> > 212992 65507 60.00 1100662 0 9613.4 10.89
> > 212992 60.00 473474 4135.4 11.27
> > After:
> > 212992 65507 60.00 1100413 0 9611.2 10.73
> > 212992 60.00 974132 8508.3 11.69
> > Using bare metal the data is similar but not as dramatic as the
> > increases from about 8.5Gb/s to 9.5Gb/s.
> > Signed-off-by: Alexander Duyck <alexander.h.duyck at redhat.com>
> Has there been any update on this patch? I submitted it just over a
> month ago now and it hasn't received any feedback. I was hoping this
> could be submitted before the merge window closes for net-next.
It will be in the next series I push later today.
Tested-by: Krishneil Singh <krishneil.k.singh at intel.com>
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