Message-ID: <49D4B799.5080902@novell.com>
Date: Thu, 02 Apr 2009 09:03:21 -0400
From: Gregory Haskins <ghaskins@novell.com>
User-Agent: Thunderbird 2.0.0.19 (X11/20081227)
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To: Avi Kivity <avi@redhat.com>
CC: Herbert Xu <herbert@gondor.apana.org.au>, anthony@codemonkey.ws,
       andi@firstfloor.org, linux-kernel@vger.kernel.org, agraf@suse.de,
       pmullaney@novell.com, pmorreale@novell.com, rusty@rustcorp.com.au,
       netdev@vger.kernel.org, kvm@vger.kernel.org,
       Mark McLoughlin <markmc@redhat.com>
Subject: Re: [RFC PATCH 00/17] virtual-bus
References: <20090402085253.GA29932@gondor.apana.org.au> <49D47F11.6070400@redhat.com> <20090402091639.GA30126@gondor.apana.org.au> <49D484F5.2000400@redhat.com> <20090402092936.GA30333@gondor.apana.org.au> <49D487A6.407@redhat.com> <49D49C1F.6030306@novell.com> <49D4A89E.5090407@redhat.com> <49D4AFF7.1050603@novell.com> <49D4B308.2030007@redhat.com>
In-Reply-To: <49D4B308.2030007@redhat.com>
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Avi Kivity wrote:
> Gregory Haskins wrote:
>
> =20
>
>>> It's more of a "schedule and forget" which I think brings you the
>>> win.  The host disables notifications and schedules the actual tx wor=
k
>>> (rx from the host's perspective).  So now the guest and host continue=

>>> producing and consuming packets in parallel.  So long as the guest is=

>>> faster (due to the host being throttled?), notifications continue to
>>> be disabled.
>>>    =20
>> Yep, when the "producer::consumer" ratio is > 1, we mitigate
>> signaling. When its < 1, we signal roughly once per packet.
>>
>> =20
>>> If you changed your rx_isr() to process the packets immediately
>>> instead of scheduling, I think throughput would drop dramatically.
>>>    =20
>> Right, that is the point. :) This is that "soft asic" thing I was
>> talking about yesterday.
>>  =20
>
> But all that has nothing to do with where the code lives, in the
> kernel or userspace.

Agreed, but note Ive already stated that some of my boost is likely from
in-kernel, while others are unrelated design elements such as the
"soft-asic" approach (you guys dont read my 10 page emails, do you? ;).=20
I don't deny that some of my ideas could be used in userspace as well
(Credit if used would be appreciated :).

-Greg


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