Date: Sat, 16 Apr 2005 10:01:33 -0700 From: John-Mark Gurney <gurney_j@resnet.uoregon.edu> To: Pyun YongHyeon <yongari@rndsoft.co.kr> Cc: freebsd-sparc64@freebsd.org Subject: Re: em(4) patch Message-ID: <20050416170133.GA16099@funkthat.com> In-Reply-To: <20050416004627.GA11603@michelle.rndsoft.co.kr> References: <20050414092608.GB2855@michelle.rndsoft.co.kr> <20050414192749.GO56487@funkthat.com> <20050415023902.GC7393@michelle.rndsoft.co.kr> <20050415030935.GQ56487@funkthat.com> <20050415042731.GD7393@michelle.rndsoft.co.kr> <20050415051112.GE7393@michelle.rndsoft.co.kr> <Pine.SOC.4.61.0504151208040.3463@tea.blinkenlights.nl> <20050415154309.GS56487@funkthat.com> <20050416004627.GA11603@michelle.rndsoft.co.kr>
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Pyun YongHyeon wrote this message on Sat, Apr 16, 2005 at 09:46 +0900:
> On Fri, Apr 15, 2005 at 08:43:09AM -0700, John-Mark Gurney wrote:
> > Sten Spans wrote this message on Fri, Apr 15, 2005 at 12:09 +0200:
> > > >With your changes JUMBO frames work here. This should also fix PR75794.
> > > >It would be really great if your changes could be comitted.
> > >
> > > Let's not forget ipv6 please, it needs this fix too,
> > > if the code is imported.
> >
> > And netatalk, netipsec and netipx too will probably need these changes..
> >
> > Another reason I haven't brought in the code quite yet...
>
> Hmm, this means we have to patch all filrewalls(pf/ipfw/ipf), carp(4)
> and possibily netgraph(4) too. I'm afraid this is not right direction
> to go. Alignment fixup would be best served in ether_input or in driver
> layer which seems to be more appropriate place. Maybe this is the
> reason why OpenBSD have such a complex alignment code in em driver.
Please make sure you know the entire problem before you say it's no
the correct way to go... Drivers like re and vge have to copy up an
entire cluster (2k), just to make alignment correct... It's even more
ugly than patching everyone to self align...
Also, IMO, it's the correct layer to put the fix up in each firewalls,
etc.. Because the driver should not magicly know that the upper layers
need an alignment.. Plus, what happens if someone happens to use foobar
which only needs 2 byte alignment... Why should we continue to fixup
packets on alignment constrained machines when this layer doesn't need
it?
Hence why I am trying to get some performance measurements to see just
the performance difference the extra mbuf allocation makes over coping
data...
--
John-Mark Gurney Voice: +1 415 225 5579
"All that I will do, has been done, All that I have, has not."
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