And last but not least, gaming performance is definitely smoother. Anyone with SLi will tell you that occassionally when playing a game, you experience a bit of lag or stuttering for no apparent reason whatsoever. Most people attribute these minor discrepancies to SLi, but what if it's something else?
There's a possibility that having it on could increase the amount of microstuttering in any given game; particularly if you're running SLi. HPET on x58 runs perfectly fine. If it runs perfectly fine, why does disabling it improve performance on my computer? Could it be bugged? My DPC latency dropped from well over to under 10, and I could definitely notice the difference. I also checked around on the net, and quite a number of other people have had a similar experience.. Then you either have device drivers on your system that are causing Rechecks in the timers, or its placebo.
Since HPET compares the actual timer value and the programmed target value on equality rather than "greater or equal", interrupts can be missed if the target time has already passed when the comparator value is written into the chip's register. In the presence of non-maskable interrupts such as System Management Interrupts that don't have a hard upper bound on their execution time, this race condition requires time-consuming re-checks of the timer after setup and is hard to avoid completely.
The Event Timer registers are memory mapped in a non-indexed scheme. This allows the CPU to directly access each register without having to use an index register. The timer register space is bytes. You can follow the question or vote as helpful, but you cannot reply to this thread. I have the same question Report abuse. Details required :. Cancel Submit.
Hi, Thank you for posting your query in Microsoft Community. Let me help you. Are you referring to High precision Event Timer? What is the make and model of your computer? How satisfied are you with this reply?
Thanks for your feedback, it helps us improve the site. In reply to A. User's post on February 28, Hi Aswin, Apologies I should have provided more detail. What is the computational cost of calling QPC? The computational calling cost of QPC is determined primarily by the underlying hardware platform. If the TSC can't be used, the system will select a different hardware time basis. This cost is dominated by the time required to access the hardware device on the motherboard.
Does QPC require a kernel transition system call? Is the performance counter monotonic non-decreasing? Can the performance counter be used to order events in time? How accurate is the performance counter?
The answer depends on a variety of factors. For more info, see Low-level hardware clock characteristics. I need to convert the QPC output to milliseconds. How can I avoid loss of precision with converting to double or float? There are several things to keep in mind when performing calculations on integer performance counters:. As a general principle, delay these computations and conversions as long as possible to avoid compounding the errors introduced. A file time is a bit value that represents the number of nanosecond intervals that have elapsed since A.
Conversion between the two requires calculating the ratio of the QPC interval and nanoseconds intervals. Be careful to avoid losing precision because the values might be small 0. Why is the time stamp that is returned from QPC a signed integer? Calculations that involve QPC time stamps might involve subtraction. By using a signed value, you can handle calculations that might yield negative values.
How can I obtain high resolution time stamps from managed code? Call the Stopwatch. GetTimeStamp method from the System. For an example about how to use Stopwatch. GetTimeStamp , see Acquiring high resolution time stamps from managed code.
Do I need to set the thread affinity to a single core to use QPC? For more info, see Guidance for acquiring time stamps. This scenario is neither necessary nor desirable. Performing this scenario might adversely affect your application's performance by restricting processing to one core or by creating a bottleneck on a single core if multiple threads set their affinity to the same core when calling QueryPerformanceCounter. Absolute clocks provide accurate time-of-day readings. They are typically based on Coordinated Universal Time UTC and consequently their accuracy depends in part on how well they are synchronized to an external time reference.
Difference clocks measure time intervals and aren't typically based on an external time epoch. QPC is a difference clock and isn't synchronized to an external time epoch or reference. When you use QPC for time-interval measurements, you typically get better accuracy than you would get by using time stamps that are derived from an absolute clock.
This is because the process of synchronizing the time of an absolute clock can introduce phase and frequency shifts that increase the uncertainty of short term time-interval measurements. QPC uses a hardware counter as its basis. Hardware timers consist of three parts: a tick generator, a counter that counts the ticks, and a means of retrieving the counter value.
The characteristics of these three components determine the resolution, precision, accuracy, and stability of QPC. If a hardware generator provides ticks at a constant rate, time intervals can be measured by simply counting these ticks. The rate at which the ticks are generated is called the frequency and expressed in Hertz Hz.
The reciprocal of the frequency is called the period or tick interval and is expressed in an appropriate International System of Units SI time unit for example, second, millisecond, microsecond, or nanosecond. The resolution of the timer is equal to the period. Resolution determines the ability to distinguish between any two time stamps and places a lower bound on the smallest time intervals that can be measured. This is sometimes called the tick resolution. This uncertainty is called a quantization error.
For typical time-interval measurements, this effect can often be ignored because the quantizing error is much smaller than the time interval being measured. However, if the period being measured is small and approaches the resolution of the timer, you will need to consider this quantizing error. Developer's Description By HP. This package supports the following driver models: High precision event timer. Full Specifications.
What's new in version 1. Release August 26, Date Added October 2, Version 1. Operating Systems. Total Downloads 2, Downloads Last Week 0.
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