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Latency issues


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#1 doveman

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Posted 10 July 2013 - 08:28 PM

I was wondering if anyone here knows much about latency in Windows and how to fix problems with high latency?

 

On my gaming system a while ago I managed to fix the problem with some help from someone analysing the traces and got it hovering as low as 19us with spikes in the low hundreds. One of the main problems was having my mouse plugged into a hub and plugging it directly into the motherboard fixed that.

 

Now I'm seeing high latency spikes, 1000us, 5000us, 7000us on both my gaming system and a system I'm building for my brother. I restored my gaming system from an early True Image backup to setup a nice clean Windows for gaming but I've checked with my other boot (the one I previously sorted the latency in) and I'm seeing similar spikes in that now as well, so I don't know if a Windows Update has done something to cause this.

 

It's hard to tell what's causing the spike from LatencyMon as it shows the ISR and DPC execution time but they can be around 40us and 170us respectively with the highest latency around 300us but then the latency will spike to 1000us or higher and these other two values are still around the same.

 

The drivers at the top of the list tend to be ndis.sys, tcpip.sys,ntoskrnl.sys, USBPORT.SYS and storport.sys on my gaming system. I'm not sure what storport.sys is doing as I looked it up and it refers to SCSI devices, which I'm not using.

 

On my brother's system, I'm not seeing storport.sys mentioned but ataport.sys instead, although that's about seventh down the list. However, a lot of the spikes do seem to be associated with HDD activity, for instance at the moment I'm doing a MBAM scan and if I pause it and start LatencyMon it hovers around 80-150us, with occasional spikes higher, but the highest being 525us in two minutes. As soon as I resume the MBAM scan, I see the hard pagefault count go up and the hard pagefault resolution time shoot up and within 30s I get a latency spike around 950us and then 3937us. Likewise if I launch Iron Portable, which I have a lot of saved tabs open in, so I suppose it's loading/writing a lot of data as it launches.

 

On my gaming system, I've updated the onboard NIC, soundcard and USB3 drivers (the first two using the drivers from the MSI website which are actually newer than the ones available direct from Realtek's sit, the USB3 drivers I got from here http://www.station-d...age/renesas.htm It doesn't seem to have helped anyway. I also tried disabling all the USB Host Controllers that don't have anything connected in Device Manager, as well as a few other devices such as the HDMI Audio and my USB Webcam.

 

 



#2 doveman

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Posted 10 July 2013 - 09:50 PM

I uninstalled Comodo Firewall v6 from my brother's system as I recalled that a firewall (ZoneAlarm I think) had previously been causing latency problems.

 

It hasn't helped and I got a DPC spike of 2500us on ataport.sys quite soon after starting LatencyMon and currently have a highest latency of 4982us. Saw about 7000 hard pagefaults as well, the majority of which were spread between two instances of svchost.exe



#3 doveman

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Posted 11 July 2013 - 06:09 PM

On the latest trace I've been advised "The latest trace shows HDD issues ("Depth queue at Init" is over 100) which explains the storport.sys issues you see".

 

I'm trying to work out what storport.sys is used for as googling it suggests it's for SCSI devices, which I don't have. In Device Manager, the AMD SATA Controller lists amd_sata.sys and amd_xata.sys, whilst the actual HDDs list disk.sys and partmgr.sys and I don't have any other storage devices connected (there's also a "Standard AHCI 1.0 Serial ATA Controller" listed, with nothing attached, so I presume there must be another controller on the MSI board that's not part of the AMD 990 chipset).

 

On my other system, I'm not seeing storport.sys flagged up (although ataport.sys is) in LatencyMon. I haven't installed the AMD Chipset driver on it yet, so the controller is listed as "Standard AHCI 1.0 Serial ATA Controller" rather than "AMD SATA". Device Manager lists for this controller atapi.sys, ataport.sys, msahci.sys, pciidex.sys and the HDD lists disk.sys and partmgr.sys as on the gaming system. 



#4 doveman

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Posted 13 July 2013 - 06:00 PM

It seems storport.sys is part of the AMD chipset drivers as it's showing up in LatencyMon on my other system now I've installed those drivers.






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