I would like to display a list of processes (Windows, C++) and how much they are reading and writing from the disk in KB/sec.
The Resource Monitor of Windows 7 has the ability so I should be able to do the same.
However I have unable to find a relevant API-call or find anything in the perfmon counters. Could anyone point me in the direction?
You can call GetProcessIoCounters to get overall disk I/O data per process - you'll need to keep track of deltas and converting to time-based rate yourself.
This API will tell you total number of I/O operations as well as total bytes.
WMI can do it, as long as you periodically snapshot it to get differential stats for some "recent" slice of time. This post presents a peculiarly mixed solution, with VBScript reading the info from WMI and Perl continually presenting the information in a Windows console. Despite the strange language mix, I think it stands as a good example of how to get at the kind of information you require (it should be quite possible to recode all of it in C++, of course).
Related
I am using Windows Portable Device API to access some MTP devices. I want to read the vendor extended properties from the device, it should look something like this:
"microsoft.com/WPDNA" or "microsoft.com/MTPZ"
It seems like this should be a quite simple task but I cannot figure it out.
I have been able to enumerate objects on a device and transfer files and so on, this was included in the WpdApiSample Application.
I also found this article that I think is what I want to do. But I don't understand how to create those queries.
Without getting into code, the short answer is to scan a range of PIDs for a given FormatID to see what kinds of data are in there. This is a debugging exercise, just for discovery purposes. I basically just write a loop: for example if I want to scan for the first 16 PIDs under the basic extended properties you'd use the WPD_PROPERTIES_MTP_VENDOR_EXTENDED_DEVICE_PROPS as FormatID and then for PID change it on each iteration and scan values 0xD101 through 0xD10F. You can usually tell from the output what may be contained in that PID location.
Once you know the PIDs for the pieces of data you want, you can write that into your code as part of your enumeration routine.
I'm experimenting my distributed clustering algorithm (implemented with MPI) on 24 computers that I set up as a cluster using BCCD (Bootable Cluster CD) that can be downloaded at http://bccd.net/.
I've written a batch program to run my experiment that consists in running my algorithm several times varying the number of nodes and the size of the input data.
I want to know the amount of data used in the MPI communications for each run of my algorithm so I can see how the amount of data changes when varying the previous mentioned parameters. And I want to do all this automatically using a batch program.
Someone told me to use tcpdump, but I found some difficulties in this approach.
First, I don't know how to call tcpdump in my batch program (which is written in C++ using the command system for making calls) before each run of my algorithm, since tcpdump requires another terminal to run in parallel with my application. And I can't run tcpdump in another computer since the network uses a switch. So I need to run it on the master node.
Second, I saw the traffic with tcpdump while my experiment was going on and I couldn't figure out what was the port used by MPI. It seems to use many ports. I wanted to know that for filtering the packages.
Third, I tried capturing whole packages and saving it to a file using tcpdump and in a few seconds the file was 3,5MB. But my whole experiment takes 2 days. So the final log file will be huge if I follow this approach.
The ideal approach would be to capture just the size field in the header of the packages and sum this up to obtain the total amount of data transmitted. In that way the logfile would be much smaller than if I were capturing the whole package. But I don't know how to do it.
Another restriction is that I don't have access to the computer disc. So I only have the RAM and my 4GB USB Flash drive. So I can't have huge logfiles.
I have already thought about using some MPI tracing or profiling tool such as those mentioned at http://www.open-mpi.org/faq/?category=perftools. I have only tested Sun Performance Analyzer until now. The problem is that I guess it will be difficult to install those tools on BCCD and maybe even impossible. In addtion to that, this tool will make my experiment take longer to end, sice it adds overhead. But if someone is familiar with BCCD and think it is a good choice to use one of those tools, so please let me know.
Hope someone have a solution.
Implementations like tcpdump won't work if there are multi-core nodes which use shard memory to communicate, anyway.
Using something like MPE is almost certainly the way to go. Those tools add very little overhead, and some overhead is always going to be necessary if you want to count messages. You can use mpitrace to write out every MPI call, and parse the resulting text file yourself. By the way, note that MPE is explicitly discussed on the bccd website. MPICH2 comes with MPE built in, but it can be compiled for any implementation. I've only found a very modest overhead for MPE.
IPM is another nice tool that does counting of messages and sizes; you should be able either parse the XML output, or use the postprocessing tools and just manually integrate the graphs (say either bytes_rx/bytes_tx by rank, or the message buffer size/count graph). The overhead for IPM is even less than for MPE, and mostly comes after the program's finished running to do the file I/O.
If you were really super worried about the overhead with either of these approaches, you could always write your own MPI wrappers using the profiling interface that wrapped MPI_Send, MPI_Recv, etc, and just counted # of bytes sent and recieved for each process, and output only that total at the end.
Does anyone know a way to programmatically retrieve the ram memory manufacturer?
Thanks!
Modern RAM chips have an additional EPROM on board that contains a lot of information about the RAM. The standard for this is SPD, or Serial Presence Detect. At least some versions of SPD include a JDEC manufacturer's code.
Look at this article for some introductory information on SPD. Not every RAM chip has the information you need, and not every BIOS exposes it, but the article should get you started on handling this stuff in those cases where it's possible.
In WINAPI, you should be able to call GetSystemFirmwareTable to retrieve the SMBIOS table, and then parse the table to extract that information.
See this
http://msdn.microsoft.com/en-us/library/ms724379%28v=VS.85%29.aspx
And this
http://dmtf.org/sites/default/files/standards/documents/DSP0134_2.7.0.pdf
The other option, as mentioned by ruslik, is to use WMI, as described here
http://msdn.microsoft.com/en-us/library/aa390423%28v=VS.85%29.aspx
(you're looking for objects of type Win32_PhysicalMemoryArray)
I'm not sure which way would be easier. Both seem hard.
I want to create a simple program which is working very similar to RAID1. It should work like this:
First i want to give the primary HDD-s drive letter and than the secondary one. I will only write to the primary HDD! If any new data is copied to the primary HDD it should automatically copy it to the secondary one.
I need some help where should i start all this? How to monitor the written data in the primary HDD? Obviously there are many ways to do what i want (i think), but i need the simpliest way.
If this isn't so complicated, than how can i handle that case if the primary HDD has two or more partition, because then i should check the secondary HDD's partition too, and then create/resize them if necessary?
Thanks in advance!
kampi
The concept of mirroring disk writes to another disk in real time is the basis for high availability, and implementing these schemes are not trivial.
The company I work for makes DoubleTake, which does real time mirroring & replication of file based IO to local or remote volumes. This is a little different than what you are describing, which appears to be block based disk/volume replication, but many of the concepts are similar.
For file based replication, there are a quite a few nasty scenarios, i'll describe a few:
Synchronizing the contents of one volume to another volume, keeping in mind that changes can occur while you are doing this. I suppose you could simply this by requiring that volumes start out totally formatted. But for people that have data that will not be a good solution!
keeping up with disk changes: What if the volume you are mirroring to is slower than the source volume? Where do you buffer? To Disk? Memory?
Anyways we use a kernel mode file system filter driver to capture the disk IO, and then our user mode service grabs this IO and forwards it to a local or remote disk.
If you want to learn about file system filtering, one of the best books (its old but good) is File System Internals, by Rajeev Nagar. Its a must read for doing any serious work with file system filters.
Also take a look at the file system filter samples on the Windows 7 WDK, its free, and they have good file mon examples that will get you seeing disk changes pretty quickly.
Good Luck!
Is there any way to determine a removable drive speed in Windows without actually reading in a file. And if I do have to read in a file, how much needs to be read to get a semi accurate speed (e.g. determine whether a device is USB2 or USB1)?
EDIT: Just to clarify, USB2 and USB1 were an example. These could be Compact Flash, could be SSD, could be a removable drive. And I am trying to determine this as fast as possible as it has a real effect on the responsiveness of the application.
EDIT: Should also clarify, this has to be done programatically. It will probably be done in C++.
EDIT: Boost answer is kind of what I was looking for (though I haven't written any WMI in C++). But I need to know what properties I have to check to determine relative speed. I don't need exact speed (like I said about the difference in speed between USB1 and USB2), but I need to know if it is going to be SLLOOOOWWW.
WMI - Physical Disks Properties is an article I found which would at least help you figure out what you have connected. I foresee things heading toward tables equating particular manufacturers and models to speeds, which is not as simple a solution as you may have hoped for.
You may have better results querying the operating system for information about the hardware rather than trying to reverse engineer it from data transfer timing information.
For example, identical transfer speeds don't necessarily mean the same technology is being used by two devices, although other factors such as seek times would improve the accuracy, if such information is available to your application.
In order to keep the application responsive while this work is done, try doing the calls asynchronously and provide some sort of progress indicator to the user. As an example, take a look at how WinDirStat handles this progress indication (I love the pac-man animation as each directory is analyzed).
Several megabytes, I'd say. Transfer speeds can start out slow, and then speed up as the transfer progresses. There are also variations because of file sizes (a single 1GB file will transfer much faster than 1GB of smaller files).
Best way to do that would be to copy a file to/from the device, and time how long it takes with your code. USB1 speed is 11Mb/s (I think), and USB2 is 480Mb/s (note those are numbers for the whole bus, not each port, so multiple devices on the same bus will change the actual numbers).
Try TerraCopy and copy one large file ~400mb - 500mb from device and to the device and you'll see the speed.
In Windows you can determine if a connected USB device is USB2 by selecting View -> "Devices by Connection" from the Device Manager and then checking to see if the device is under a USB2 controller (USB2 Enhanced Host Controller).
Note that this doesn't mean your device will actually perform at the higher speeds though, you would still need actual throughput tests for that. The Sisoft Sandra benchmarking software lists removable hard drives as supported in its feature list.
EDIT: Due to clarification in original question, I have submitted a new answer.
Consider the number of things that could affect data transfer speed:
The speed of the bus used to connect the device to the system. This is unlikely to be your bounding factor unless it's connected via USB1.
For hard drives, rotational speed and seek time matter. 7200 RPM drives will read and write blocks of data faster than 5400 RPM drives.
Optical and magnetic drives usually spin down when not in use, so the first access will take orders of magnitude more than the second access.
The filesystem used on the particular device.
Caching of data and filesystem metadata. The less metadata is cached, the more a magnetic or optical drive has to seek to figure out where the data is.
Data access pattern. Accessing a small number of large, contiguous files is almost always faster than accessing a large number of small files scattered around the disk.
File system fragmentation
You might be able to work up some heuristics based on the various characteristics of the devices you expect to see, but in general there's no good way to figure out transfer speed for a particular combination of bus, media, filesystem, and data access pattern without actually measuring it. If you decide to measure, try to simulate your final access pattern as closely as possible.
I'm going to borrow Raymond Chen's crystall ball and say that you really don't want this. You probably want to use asynchronous I/O. If you do not get the result of your I/O within a second, you want to check how much did happen. Take the inverse of that number, and you have a good estimate to quote to the user.
If nothing happened after a second, you may be in for a surprise. But even that can happen. For instance, a harddisk may need a second to spin up. Just poll every second until something has happened.