Client Connection Problems (1 Viewer)

mm1352000

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  • September 1, 2008
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    Thanks for the update :)

    I have found some posts complaining about the poor performance of the Compute Stick's built-in WLAN, but I don't understand how it can be so much worse than a laptop.
    Yes, anandtech's review mentions this:
    http://www.anandtech.com/show/9167/intel-compute-stick-review/3
    The numbers appear downright bad even when we consider that we are looking at a 1x1 802.11n connection. Surprisingly, when connected to another router in the same place, we were getting transfer rates in the order of 48 - 50 Mbps. However, the results graphed above have the numbers from the same router with the clients at the same location. Users will probably be seeing a wide range in the performance of the WLAN component.

    If you compare a laptop with the same NIC (chip), my guess is that the most important differences would be power/heat and aerial (TX/RX) limitations due to the compute stick's small physical size. Don't underestimate the effects of those differences.

    If you compare against other NICs used in laptops, additional reasons such as too much resource contention and poor hardware and/or driver design and/or implementation come into play.

    Ultimately I don't think it's important to understand how, because it's unlikely we can do much to fix it...

    I tried out LatencyMon, but don't really understand the results.
    Well I have never used LatencyMon (it's not compatible with XP). However I can make some interpretation of your results based on DPC Latency Checker, which gives a graph like this:
    upload_2016-3-18_9-36-22.png


    In your results, you have "Highest measured interrupt to process latency (µs)" and "Highest measured interrupt to DPC latency (µs)" of 827.904212/596.736153, 15631.876002, 15601.155994 and 1234.944316/1193.472306 respectively for your tests. The first result would be in the yellow section of the DPC Latency Checker graph, while the other two results would be in the red.

    What these numbers mean is that your system stalled for up to 15600 us (15 ms) waiting for certain driver tasks to complete. To us 15 ms is not very long, but for a CPU which needs to be handling video and/or audio that's a very (very!) long time. The conclusion that LatencyMon gives with the results appears to be correct:
    Your system appears to be having trouble handling real-time audio and other tasks. You are likely to experience buffer underruns appearing as drop outs, clicks or pops. One or more DPC routines that belong to a driver running in your system appear to be executing for too long. At least one detected problem appears to be network related. In case you are using a WLAN adapter, try disabling it to get better results. One problem may be related to power management, disable CPU throttling settings in Control Panel and BIOS setup. Check for BIOS updates.

    What more can we say? Well, lower in the results (and in the screenshot) you can see the cause(s) of high latency.

    For ISRs (interrupt service routines), the sdbus.sys driver (SecureDigital Bus Driver, Microsoft Corporation) seems to be causing problems. It can take up to ~800 us to complete its ISRs. Fortunately this only seems to happen occasionally - 1 out of 213284 or 5 out of 370180 ISRs.

    For DPCs (deferred procedure calls), the causes mentioned in the results are mixed (eg. sdbus.sys and ntoskrnl.exe). For that reason I think it's better to look at the screenshot. There you can see that several drivers - tcpip.sys, usbport.sys and sdbus.sys - have high DPC latency. The fact that sdbus.sys comes up again and is listed as "Driver with highest DPC total execution time" in all the results almost certainly confirms it has a problem. tcpip.sys is related to networking, and I suspect usbport.sys is as well (NIC connected via internal USB interface).

    Any other ideas what I can do (besides giving up on the built-in LAN and getting a USB WiFi dongle) would be most welcome!
    All that I can say is:
    1. If you don't use the micro-SD card slot, consider disabling it; if you do use it, consider whether the SD card you're using could be too slow, could benefit from defragmentation etc.
    2. Check that you're running the latest drivers. In some cases drivers that come directly from the chip vendor may be better. For example, if the WLAN NIC is from Realtek, try to get the driver from Realtek rather than Intel.

    If I were you, I'd be getting a USB dongle.
     

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