What Does Window Auto Tuning Do
Problem is, that it is really hard to tell why a system used a specific window size since we have that funky auto tuning stuff these days. It was a lot easier back when we all ran Windows XP and earlier:-). Aug 05, 2016 Microsoft introduced a feature called Window Auto-Tuning back in Windows Vista, and has made it part of any newer version of Windows as well. Set to on by default, it is designed to improve performance for programs that receive TCP data over a network. Nov 14, 2012 947239 Description of the Receive Window Auto-Tuning feature for HTTP traffic on Windows Vista-based computers For more information about the autotuning feature issue, click the following article number to view the article in the Microsoft Knowledge Base.
Applies To: Windows Server 2012
This topic contains the following sections.
Determining the correct tuning settings for your network adapter depend on the following variables:
The network adapter and its feature set
The type of workload performed by the server
The server hardware and software resources
Your performance goals for the server
If your network adapter provides tuning options, you can optimize network throughput and resource usage to achieve optimum throughput based on the parameters described above.
The following sections describe some of your performance tuning options.
Enabling Offload Features
Turning on network adapter offload features is usually beneficial. Sometimes, however, the network adapter is not powerful enough to handle the offload capabilities with high throughput. For example, enabling segmentation offload can reduce the maximum sustainable throughput on some network adapters because of limited hardware resources. However, if the reduced throughput is not expected to be a limitation, you should enable offload capabilities, even for this type of network adapter.
Note
Some network adapters require offload features to be independently enabled for send and receive paths.
Enabling Receive Side Scaling (RSS) for Web Servers
RSS can improve web scalability and performance when there are fewer network adapters than logical processors on the server. When all the web traffic is going through the RSS-capable network adapters, incoming web requests from different connections can be simultaneously processed across different CPUs.
It is important to note that due to the logic in RSS and Hypertext Transfer Protocol (HTTP) for load distribution, performance might be severely degraded if a non-RSS-capable network adapter accepts web traffic on a server that has one or more RSS-capable network adapters. In this circumstance, you should use RSS-capable network adapters or disable RSS on the network adapter properties Advanced Properties tab. To determine whether a network adapter is RSS-capable, you can view the RSS information on the network adapter properties Advanced Properties tab.
RSS Profiles and RSS Queues
RSS predefined profiles are new in Windows Server 2012.
The default profile is NUMA Static, which changes the default behavior from previous versions of the operating system. To get started with RSS Profiles, you can review the available profiles to understand when they are beneficial and how they apply to your network environment and hardware.
For example, if you open Task Manager and review the logical processors on your server, and they seem to be underutilized for receive traffic, you can try increasing the number of RSS queues from the default of 2 to the maximum that is supported by your network adapter. Your network adapter might have options to change the number of RSS queues as part of the driver.
Increasing Network Adapter Resources
For network adapters that allow manual configuration of resources, such as receive and send buffers, you should increase the allocated resources. Some network adapters set their receive buffers low to conserve allocated memory from the host. The low value results in dropped packets and decreased performance. Therefore, for receive-intensive scenarios, we recommend that you increase the receive buffer value to the maximum.
Note
If a network adapter does not expose manual resource configuration, it either dynamically configures the resources, or the resources are set to a fixed value that cannot be changed.
Enabling Interrupt Moderation
To control interrupt moderation, some network adapters expose different interrupt moderation levels, buffer coalescing parameters (sometimes separately for send and receive buffers), or both.
You should consider interrupt moderation for CPU-bound workloads, and consider the trade-off between the host CPU savings and latency versus the increased host CPU savings because of more interrupts and less latency. If the network adapter does not perform interrupt moderation, but it does expose buffer coalescing, increasing the number of coalesced buffers allows more buffers per send or receive, which improves performance.
Performance Tuning for Low Latency Packet Processing
Many network adapters provide options to optimize operating system-induced latency. Latency is the elapsed time between the network driver processing an incoming packet and the network driver sending the packet back. This time is usually measured in microseconds. For comparison, the transmission time for packet transmissions over long distances is usually measured in milliseconds (an order of magnitude larger). This tuning will not reduce the time a packet spends in transit.
Following are some performance tuning suggestions for microsecond-sensitive networks.
Set the computer BIOS to High Performance, with C-states disabled. However, note that this is system and BIOS dependent, and some systems will provide higher performance if the operating system controls power management. You can check and adjust your power management settings from Control Panel or by using the powercfg command. For more information, see Powercfg Command-Line Options
Set the operating system power management profile to High Performance System. Note that this will not work properly if the system BIOS has been set to disable operating system control of power management.
Enable Static Offloads, for example, UDP Checksums, TCP Checksums, and Send Large Offload (LSO).
Enable RSS if the traffic is multi-streamed, such as high-volume multicast receive.
Disable the Interrupt Moderation setting for network card drivers that require the lowest possible latency. Remember, this can use more CPU time and it represents a tradeoff.
Handle network adapter interrupts and DPCs on a core processor that shares CPU cache with the core that is being used by the program (user thread) that is handling the packet. CPU affinity tuning can be used to direct a process to certain logical processors in conjunction with RSS configuration to accomplish this. Using the same core for the interrupt, DPC, and user mode thread exhibits worse performance as load increases because the ISR, DPC, and thread contend for the use of the core.
System Management Interrupts
Many hardware systems use System Management Interrupts (SMI) for a variety of maintenance functions, including reporting of error correction code (ECC) memory errors, legacy USB compatibility, fan control, and BIOS controlled power management. The SMI is the highest priority interrupt on the system and places the CPU in a management mode, which preempts all other activity while it runs an interrupt service routine, typically contained in BIOS.
Unfortunately, this can result in latency spikes of 100 microseconds or more. If you need to achieve the lowest latency, you should request a BIOS version from your hardware provider that reduces SMIs to the lowest degree possible. These are frequently referred to as “low latency BIOS” or “SMI free BIOS.” In some cases, it is not possible for a hardware platform to eliminate SMI activity altogether because it is used to control essential functions (for example, cooling fans).
Note
The operating system can exert no control over SMIs because the logical processor is running in a special maintenance mode, which prevents operating system intervention.
Performance Tuning TCP
You can performance tune TCP using the following items.
Details are provided in the following sections.
TCP Receive Window Auto-Tuning
Prior to Windows Server 2008, the network stack used a fixed-size receive-side window that limited the overall potential throughput for connections. One of the most significant changes to the TCP stack is TCP receive window auto-tuning. You can calculate the total throughput of a single connection when you use this fixed size default as:
Total achievable throughput in bytes = TCP window * (1 / connection latency)
For example, the total achievable throughput is only 51 Mbps on a 1 GB connection with 10 ms latency – which is a reasonable value for a large corporate network infrastructure.
With auto-tuning, however, the receive-side window is adjustable, and it can grow to meet the demands of the sender. It is entirely possible for a connection to achieve the full line rate of a 1 GB connection. Network usage scenarios that might have been limited in the past by the total achievable throughput of TCP connections can now fully use the network.
Windows Filtering Platform
The Windows Filtering Platform (WFP) that was introduced in Windows Vista and Windows Server 2008 provides APIs to non-Microsoft independent software vendors (ISVs) to create packet processing filters. Examples include firewall and antivirus software.
Note
A poorly written WFP filter can significantly decrease a server’s networking performance.
For more information, see Windows Filtering Platform in the Windows Dev Center.
TCP Parameters
The following registry keywords from Windows Server 2003 are no longer supported, and they are ignored in Windows Server 2012, Windows Server 2008 R2, and Windows Server 2008.
TcpWindowSize
NumTcbTablePartitions
MaxHashTableSize
The benefits, advantages and fun to be had with car chip tuning…
Tuning your car’s engine takes some skill and know-how but once you have started to master it you will find yourself enjoying hours of fun.
What is meant by the phrase “engine tuning”. Let’s start by accepting that the engine comes in many different types and shapes. This explanation is a generic description of on how a car is tuned. The aim is to get readers up to a speed where they can rev up their game by talking to aficionados and grease monkeys who can be found aplenty on the numerous online car forums.
A lot of people think that a car is tuned when it’s running at the top of its game. These people often think this is achieved simply by the car getting breathed on at a full service and adjustments being made to the vehicle’s factory specifications.
For some people tuning means enhancing the car’s performance and running capabilities so it’s better than it was when it was transported out of the manufacturer and set up and polished at the dealership.
What is certain though is that there is no doubt there are lots of opportunities to improve an engine and the body in which it arrives because so many manufacturers these days are using conservative settings and cheaper production methods.
Having decided you would like to attempt to tune your car what does it involve and how do you get started?
Here a number of methods for tuning a variety of popular models and engine types will be presented.
The main thrust will be to maximize the car’s performance, but, in so doing, the methods used are also available to use to maximize the car’s economy pushing its power unit into the most efficient range.
Boosting a car’s performance
Begin by making sure the car is in tip-top conditions. A full service is required. The engine needs to be running as it is meant to be. New oil, filter, spark plugs need to be added. If any leads are old they also need to be replaced.
Check the engine’s compression and get any major issues – like worn piston rings or worn or broken valves rectified. Monitor the valve clearance to prevent a significant loss of power.
Tuning a carburettor engine
Carburettor engines tend to rely on the spark being distributed by a breaker. This is done with a very basic mechanical advance when the Revs Per Minute are rising. Timing a spark to happen just a fraction earlier a more complete burn cycle can be achieved. This converts the fuel and air mix more efficiently into the power for which we are looking. Beware though because advancing it too much is a bad thing. The engine starts to knock.
In general the desired effect can be achieved by a simple trial and error approach. This can be done by gradually turning up the advance until the engine begins to knock, when the advance can be reversed until a good balanced setup is in place.
Balancing the timing and spark duration helps improve both economy and power because the engine is efficient.
Employing a strobe light linked to the pulse of the spark plug pulse effectively freezes the engine and shows the timing mark, which is on the pulley at the bottom of the cam belt. Here, in most cases, there is a tiny groove and a small notch on the engine.
Use some white paint to mark the notch and groove and the timing mark will show up when hit by the strobe, to enable better adjustment of the engine’s timing.
When the distributor housing is rotated the timing can be adjusted by retarding it or advancing it. This sort of adjustment needs to be tackled gradually. The engine will also require testing when it is under load and at the full range of rpm.
What Does Window Auto Tuning Do On Iphone
The best environment, which enables adjustments to be made live, involves the use of a rolling road dynometer. If the fuel needs to be increased to match the air that is taken a larger jet is needed.
Setting up a carburettor can take a lot of practice. When the car has twin carburettors then the job becomes even harder.
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Most carburettors are delivered with the right jet sizes. They should only be upgraded when the engine requires dramatic alterations and the amount of air taken in increases significantly.
Fuel to air delivery need to be matched. Of course in modern engines with fuel injection this is becoming a moribund skill .
Tuning a fuel injection engine
Compared to a carburettor engine, one that is fuel injected is a much more sophisticated affair. Timing when a spark is delivered and adjusted and the amount of fuel required is very different.
The old fashioned mechanical distribution of a spark was in no way an ideal solution. It meant that engine was not able to run at peak efficiency a lot of the time.
The fact is that the timing of each spark needs to vary much more than allowed by a linear curve. To tackle this issue computers have been fitted to cars so that a fuel and timing map can be stored. This operates across a variety of intake conditions and loads to enable optimum running.
The majority of today’s engines now operate on closed loops. This means the parameters for each combustion cycle are set by the one before. The exhaust is monitored for oxygen emissions to check whether the car is running lean or rich and if the fuel being taken in is being adjusted to match.
A lot of the most popular engines are able to adjust themselves so they run at their optimum settings. Roughly every 200 miles to keep running efficiently they are able to automatically make the necessary adjustments.
Driving style, temperatures and different grades of fuel are taken into account. There is a little a keen do-it-yourself tuner can do except change the chip when the computer controls a car’s fuel delivery and timing. But more of this later.
If the engine is naturally aspirated it may well be possible to squeeze another 10 per cent or so of power by tightening the maps for fuel delivery and timing. As said before it is common for manufacturers to set their engines conservatively.
Tuning a turbo engine.
In turbo engines fuel delivery and spark timing are as essential as they are in fuel-injected versions. Indeed the same advice applies to turbo engines. The difference is that the benefits are much more noticeable thanks to the turbo. A turbo pushing an increased quantity of air into the engine, generates a lot more power.
As the turbo is the engine’s heart and soul it needs attention. By matching what drives exhaust and intake compression to the air can seriously affect a car’s power band.
Turbos can be hybridized with a turbo casing from an original equipment manufacturer (OEM) and by upgrading its internals. Another method is to either change the existing turbo with a larger version or to add a second turbo. The only consideration is how much power is required.
Those engines that date from the last century are known for being a challenge to remap. This means that the options are limited to piggy back devices or risky chip changes.
Since 2000 though most models have been supplied with On-Board Diagnostics Parameter IDs (OBDII) ports – codes that request the vehicle’s data. These enable a car’s computer to change or update the program controlling air/fuel ratios, ignition timing, and a whole lot more. Windows software like TOAD can do advanced tuning.
On these more modern turbo engines the computer tends to administer the boost and waste gates as well as the timing and fuelling providing much more scope for increasing power. Indeed, power gains of 40 per cent are relatively easy using stock parts and a simple remapping.
Other ways of tuning an engine.
Armed with the characteristics of timing there are many other modifications that can be done to a car’s power unit.
The huge number of modifications available for boosting an engine’s tune includes adding a sports camshaft that will increase the power, balancing the power unit so it’s able to run at higher RPM, and adjusting the timing. In addition a beneficial effect will be found by increasing the duration of an engine’s compression, induction, exhaust and bang cycles.
Causing the air to move though an engine more quickly is another priority for the home tuner. Sports exhausts, sport catalysts and head work like polishing and porting have further benefits for enhancing the power band.
With a turbo there are additional options available too. Intercoolers reduce intake air temperature and encourage larger power gains. A turbo can also be upgraded by either choosing a bigger turbo or getting and existing unit hybridized with improved internals.
Blow off and wastegate controls can be adjusted to boost power generated by an engine.
Tuning cars with chips
Typical DIY tuning kit
In spite of all the useful advice already given, it is a fact that the days of being able to simply get under the bonnet of a car with a set of spanners in an endeavour to make a car go faster are distinctly numbered.
The computers that operate modern engines (ECUs) have increasingly rapidly taken over a large number of the functions and controls that determine every aspect of how an engine is managed from timing to fuelling.
It means engines are now pumping out bigger and better power, coupled with cleaner burns and more reliable engines, but by no means is it the end of the road for the home tuner.
The map or program, call it what you will, is easily up rated in many of today’s cars. Chip tuning is a very loose term for describing processes for remapping a car’s engine.
Engine remaps and chip tuning are very similar but here the concentration is one the latter. The imperfect term is thought to derive from distant days when chips were not easily updateable and “reflashed”.
Nowadays chip removal and replacement is coming back as an important option, not least because some ECUs are locked. This means that replacing the chip is the only choice even though these would often have to be soldered and thanks to delicate chips, are likely to fail.
EPROMS are read-only memories whose contents can be cleared (by various means including with ultraviolet lights) and reprogrammed. These were able to be removed, reflashed and reinstalled.
Chip replacements used to be the sole way of changing a car’s map but it is now easily possible with standardized diagnostic ports.
Recently cars have been coming equipped with on board diagnostic ports which enable the uploading of a fresh map.
Chip tuning is not really something that can easily be done by the home tuner. To embark upon the task requires a detailed knowledge of the engine in question. Then the tuner has ideally to have access to a complete set of diagnostic equipment that is attached to a rolling road that allows “live” adjustments to be made to the mapping.
It is not just a matter of simply adjusting a few numbers and benefiting from a significant power gain.
DIY chip tuners also face the risk of bad flashes where the computer crashes and cannot be recovered. In the absence of a suitable restoration image either a new computer or an expensive visit to a main dealer may be required.
Chip tuning is best when it is possible to insert a custom map which takes into account a car’s characteristics, strong and weak, and whatever other modifications have been done to the car.
A few companies offer replacement chips which have a sportier feel. There are performance chips which can be installed either by a home tuner or a specialist installer.
Windows Auto Tuning
Often off the shelf these maps are designed to be fitted in a large variety of vehicles. Although these offer benefits over the standard equipment they will never be as good as a custom map that has been specifically designed for a particular car and a driver’s idiosyncratic driving style.
In general most cars will demonstrate the benefits of a replacement chip but to see the really large gains turbocharged applications are required. In a Naturally Aspirated engine (NASP) power gains are generally between 10 and 20 per cent, but in turbo engines these power gains grow to about 40 per cent in a petrol engine and 30 per cent in a turbo diesel engine.
Even cars that receive relatively low power gains from remaps are going to be more lively drives.
Peak power gain figures are just a tiny proportion of the tuning equation. The first and foremost reasons for leaping into the fine art and science of chip tuning is to have an impact of how an engine responds under acceleration and how its torque curves.
Tcp Window Auto Tuning
There are downsides, however, there is an increased requirement for servicing and car maintenance on a regular basis.
By chip tuning a vehicle the safe margin of error that the manufacturer has built in is eroded by the action. This is an important consideration because those safe margins are there to protect against the effects of filling up with low quality fuel and the sort of wear and tear that comes with a car being services at longer intervals.
Any remap should only take place when a car has been serviced and is running in the best condition possible.
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Now, that you’ve read a basic intro guide to car tuning, time to delve deeper into the details with: Getting Started With Car Tuning: Part 2 the technical details