Started by norain, July 19, 2012, 01:33:47 PM
Quote from: BenYeeHua on July 20, 2012, 09:57:32 AMSo you has been using latencymon and found that the DPC latency are cause by 2 drivers that used by firewire and USB ports?As I know, having a high DPC latency on USB are caused by third-party usb 3.0 and updating the driver or disable maybe can solve it.I don't have a Firewire, and had Google it, some DPC latency are caused by Displaycard or Wifi driver(can be solved/reduced by using WLAN Optimizer).
Quote from: bitsum.support on July 20, 2012, 02:48:20 PMPretty much what I said - an I/O device hogging a bus . Some bad drivers could cause such issues, sure. Some USB 3.0 drivers may be too poorly optimized to handle the throughput that some USB 3.0 devices can handle. Same could go for Firewall.What REALLY needs done .. and this is what Microsoft's kernel does .. is throttle the I/O activity. Actually limit it. Now, Process Lasso's 'Hard Throttling' does this to CPU activity, but it doesn't take much CPU activity to issue I/O requests, and is a dangerous operation anyway. Thus, I don't recommend it here.
Quote from: bitsum.support on July 20, 2012, 05:19:55 PMOh, and it is not the old days anymore, but back in the old days, adjusting your PCI latency could help a lot with DPC latency. It is the time a device is allowed to hold the PCI bus. Lower it, and it ensures more devices have a chance to get the bus. Raise it, and bandwidth on the bus is improved for particular devices.
Quote from: DeadHead on July 20, 2012, 08:11:56 PMFYI, software such as "Easy Tune" (and similar) triggers DPC Latency spikes. In other words, spikes in DPC Latency is not always caused by hardware and/or faulty drivers. Be sure to check your systems thoroughly when using that type of analyzing software.
Quote from: BenYeeHua on July 20, 2012, 07:29:32 PMSo by throttling I/O is difficult to prevent I/O Request Packet (IRP) issues, other way to lower DPC latency?
QuoteAnd why windows 8 can (make other program) operating smooth like having a SSD(by using hdd as system disk)?By reducing page fault?
Quote from: bitsum.support on July 21, 2012, 03:15:28 AMAgain, depends on the cause. The *exact* cause must be isolated. You've partially done that, but to be more precise would require serious digging (time being money, cheaper to buy a new PC ;o). Anyway, no other way I know of, though Google may help more than me, but I'm sure you've been through it for ages .
QuoteThat is a good question. It does run snappy, or at least appears to (part could be illusions). I am not sure what they did, to be honest. Perhaps their 'page out' (to keep free cache space in RAM) is less aggressive, that is a possibility. Perhaps they increased SuperFetch with some 'default' set of common data to prefetch and try to keep cached, instead of having it populated as the machine is used. They may have removed a lot of unnecessary code from the kernel too, sanity checks and such that they could feel comfortable removing from the release build since this NT6 derived kernel is now more mature than it once was. I will have to research this .I will read their official docs about their improvements, and go through their code. I will let you all know when I know more.
Quote from: bitsum.support on July 21, 2012, 10:41:43 PMAlso, one thing we also must remember, as I'm reminded of from time to time, a default Windows 7 or Windows XP install is pretty darn snappy itself. I will post details as I know of the specific optimizations they made.
QuoteHow this works is that each PCI device that can operate in bus-master mode is required to implement a timer, called the Latency Timer, that limits the time that device can hold the PCI bus. The timer starts when the device gains bus ownership, and counts down at the rate of the PCI clock. When the counter reaches zero, the device is required to release the bus. If no other devices are waiting for bus ownership, it may simply grab the bus again and transfer more data.
Quote from: bitsum.support on July 22, 2012, 03:11:31 PMYea, sadly haven't seen it as a BIOS option in a long time. There is also some software that lets you set it per-device on your PC, dynamically - at runtime. Apparently this is a 'setting' of many Windows device drivers. I can not say whether this utility worked or not, but it is somewhere out there ... Nice little utility, would show the current PCI Latencies of a list of devices, and let you change them - an operation that seemed to persist.
Quote from: BenYeeHua on July 22, 2012, 03:57:07 PMPCI Latency Tool?All the similar tool are outdated.So be careful when using it, by buying a PCI-E sound card is a better way to avoid it(when DPC latency has no problem), or using ASIO buffer is a better way also(but with increased delay).