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Re: [Qemu-devel] [PATCH v5 1/2] e1000: add interrupt mitigation support
From: |
Andreas Färber |
Subject: |
Re: [Qemu-devel] [PATCH v5 1/2] e1000: add interrupt mitigation support |
Date: |
Wed, 31 Jul 2013 12:05:34 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130620 Thunderbird/17.0.7 |
Am 31.07.2013 10:13, schrieb Vincenzo Maffione:
> 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 "mit", e.g.
"mitigation" in example and property definitions below.
>
> 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 <address@hidden>
> ---
> hw/net/e1000.c | 131
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 128 insertions(+), 3 deletions(-)
>
> diff --git a/hw/net/e1000.c b/hw/net/e1000.c
> index fdb1f89..32014c2 100644
> --- a/hw/net/e1000.c
> +++ b/hw/net/e1000.c
[...]
> @@ -1385,6 +1508,8 @@ static Property e1000_properties[] = {
> DEFINE_NIC_PROPERTIES(E1000State, conf),
> DEFINE_PROP_BIT("autonegotiation", E1000State,
> compat_flags, E1000_FLAG_AUTONEG_BIT, true),
> + DEFINE_PROP_BIT("mitigation", E1000State,
> + compat_flags, E1000_FLAG_MIT_BIT, true),
> DEFINE_PROP_END_OF_LIST(),
> };
>
Regards,
Andreas
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