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Date: Thu, 8 Oct 2009 22:19:48 +1100 (EST)
From: Ian Smith <smithi@nimnet.asn.au>
To: rihad <rihad@mail.ru>
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Cc: freebsd-net@freebsd.org, Eugene Grosbein <eugen@kuzbass.ru>,
	Robert Watson <rwatson@freebsd.org>, Luigi Rizzo <rizzo@iet.unipi.it>,
	Julian Elischer <julian@elischer.org>
Subject: Re: dummynet dropping too many packets
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On Wed, 7 Oct 2009, rihad wrote:

 > Robert Watson wrote:
 > 
 > > I would suggest making just the HZ -> 4000 change for now and see how it
 > > goes.
 > > 
 > OK, I will try testing HZ=4000 tomorrow morning, although I'm pretty sure
 > there still will be some drops.

Even if there are, I'd like to know what (rough) percentage in increased 
interrupt load you experience with HZ=4000 vs 1000 on that beast in your 
application, or of any discernable effects on other running processes?

[Thanks guys for this interesting thread]

 > > > Can someone please say how to increase the "ifnet transmit queue sizes"?
 > > 
 > > Unfortunately, I fear that this is driver-specific, and in the case of bce
 > > requires a recompile.  In the driver init code in if_bce, the following
 > > code appears:
 > > 
 > >         ifp->if_snd.ifq_drv_maxlen = USABLE_TX_BD;
 > >         IFQ_SET_MAXLEN(&ifp->if_snd, ifp->if_snd.ifq_drv_maxlen);
 > >         IFQ_SET_READY(&ifp->if_snd);
 > > 
 > > Which evaluates to a architecture-specific value due to varying pagesize.
 > > You might just try forcing it to 1024.
 > > 
 > I think I'll try this too, if HZ=4000 doesn't help, thanks a lot.
 > In the long run we'll switch to some high-quality 10 GiGE cards.