Re: [Qemu-devel] [PATCH v6] e1000: add interrupt mitigation support

["Andreas Färber" <afaerber@suse.de>]

Am 05.08.2013 11:27, schrieb Stefan Hajnoczi:
> On Fri, Aug 02, 2013 at 06:30:52PM +0200, Vincenzo Maffione wrote:
>> This patch partially implements the e1000 interrupt mitigation mechanisms.
>> Using a single QEMUTimer, it emulates the ITR register (which is the newer
>> mitigation register, recommended by Intel) and approximately emulates
>> RADV and TADV registers. TIDV and RDTR register functionalities are not
>> emulated (RDTR is only used to validate RADV, according to the e1000 specs).
>>
>> RADV, TADV, TIDV and RDTR registers make up the older e1000 mitigation
>> mechanism and would need a timer each to be completely emulated. However,
>> a single timer has been used in order to reach a good compromise between
>> emulation accuracy and simplicity/efficiency.
>>
>> The implemented mechanism can be enabled/disabled specifying the command
>> line e1000-specific boolean parameter "mitigation", e.g.
>>
>>     qemu-system-x86_64 -device e1000,mitigation=on,... ...
>>
>> For more information, see the Software developer's manual at
>> http://download.intel.com/design/network/manuals/8254x_GBe_SDM.pdf.
>>
>> Interrupt mitigation boosts performance when the guest suffers from
>> an high interrupt rate (i.e. receiving short UDP packets at high packet
>> rate). For some numerical results see the following link
>> http://info.iet.unipi.it/~luigi/papers/20130520-rizzo-vm.pdf
>>
>> Signed-off-by: Vincenzo Maffione <v.maffione@gmail.com>
>> ---
>> Added pc-*-1.7 machines (default machine moved to pc-i440fx-1.7).
>>
>>  hw/i386/pc_piix.c    |  18 ++++++-
>>  hw/i386/pc_q35.c     |  16 ++++++-
>>  hw/net/e1000.c       | 131 +++++++++++++++++++++++++++++++++++++++++++++++++--
>>  include/hw/i386/pc.h |   8 ++++
>>  4 files changed, 167 insertions(+), 6 deletions(-)
> 
> I will merge this into my net tree soon but I'd like to wait for
> Andreas' review to make sure he's comfortable with the machine type
> changes too.

I'm okay with the machine changes, just not comfortable reviewing the
net code. Feel free to add a "Reviewed-by: Andreas Färber
<afaerber@suse.de> (for pc-* machines)" if you wish.

Andreas

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