From: Wei Liu <wei.liu2@citrix.com>
Date: Mon, 26 Aug 2013 11:59:37 +0000 (+0100)
Subject: xen-netback: remove page tracking facility
X-Git-Tag: v3.12-rc1~132^2~165^2~2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=43e9d1943278e96150b449ea1fa81f4ae27729d5;p=pandora-kernel.git

xen-netback: remove page tracking facility

The data flow from DomU to DomU on the same host in current copying
scheme with tracking facility:

       copy
DomU --------> Dom0          DomU
 |                            ^
 |____________________________|
             copy

The page in Dom0 is a page with valid MFN. So we can always copy from
page Dom0, thus removing the need for a tracking facility.

       copy           copy
DomU --------> Dom0 -------> DomU

Simple iperf test shows no performance regression (obviously we copy
twice either way):

  W/  tracking: ~5.3Gb/s
  W/o tracking: ~5.4Gb/s

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Matt Wilson <msw@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

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