Channel 9 - Discussions by TimP

Coffeehouse - so..uh... Nikon wins.. hands down.

TimP — Thu, 10 Apr 2008 23:51:34 GMT

Hope this isn't a thread hijack, but since DigitalDud mentioned it, is there any consensus on a good low to mid end point and shoot camera? I'll be travelling this summer and would like to take some pictures. Preferably under $250 or so.

Tech Off - Methods of protecting .net exe's from decompilation?

TimP — Sat, 29 Mar 2008 08:02:41 GMT

If you're really that concerned, make it a web app or something and run it on a box you own. If you think your competitors will go to any length to reverse engineer your work, then don't give it out the EXE at all.

I don't think many customers would be keen on this, though. Eventually if you make it too cumbersome to even use they'll go elsewhere regardless.

Tech Off - "virtual" printer

TimP — Wed, 19 Mar 2008 02:06:37 GMT

Couldn't you use generic PCL6 drivers on Vista? Unless this printer has fancy features you need to exploit, any old PCL6 driver should do it.

Tech Off - Rootkits on x64 Vista: Are they feasible?

TimP — Fri, 14 Mar 2008 09:36:24 GMT

I've noticed my desktop icons seem to be refreshing a lot more than I remember in the past and any suspicious behavior always triggers paranoid malware fears in my mind, but that's beside the point. I was thinking about the rootkit "epidemic" and was wondering if they're still a legitimate risk on x64 Vista.

As far as I understand, rootkits that effectively hide their presence (i.e. not showing up in the process list, registry, file system, etc.) require a kernel mode component to intercept queries for information that could reveal them and return a modified result with themselves omitted.

With x64 Vista closing the door on unsigned kernel drivers, is it still possible to have a truly stealthy rootkit (obviously moot if the rootkit is a signed)?

Have there been any stories of Vista rootkits in the wild?

Tech Off - C Standard Library string.h question involving strtok()

TimP — Sat, 08 Mar 2008 03:56:07 GMT

strtok uses a static pointer to keep track of where it is, that's why it's not thread safe. I took a look at the source code (strtok is only a handful of lines long, /glibc-2.7/string/strtok.c in the tarball) and it seems to only manipulate pointers pointing to your original string, so there's no need to free anything it returns. Just free the buffer the string was in at the end if it was dynamically allocated.

Tech Off - Windows 7

TimP — Thu, 06 Mar 2008 00:38:31 GMT

It's always interesting to speculate about these things, but the NT kernel is inseparably tied to the rest of the operating system. If you swapped the kernels, you would probably spend the bulk of your time writing compatibility layers in Linux/Unix to mimic NT kernel features.

Besides, I can't think of any value added by using a Linux kernel.

(and I'm a Linux user too, so this isn't a MS shill post)

Tech Off - Re-installing Windows XP onto a second hard drive

TimP — Sun, 02 Mar 2008 21:37:19 GMT

Lloyd_Humph wrote:

What does RAM have to do with it? I think you're confusing yourself here. As for expensive RAM, it probably was expensive at first. You can probably get 1GB for the same price you paid.

I'm guessing it's Rambus RD-RAM. Last time I checked (a few years ago), you could get 1GB of DDR RAM for around $130 and 512MB of RD-RAM was around $200. I don't know if they even sell Rambus RAM anymore (I don't see any one Newegg). I remember doing an estimate and finding that it would be cheaper to buy a new motherboard and 1GB of DDR RAM than buying an additional 512MB of RD-RAM.

Tech Off - Why does my C program run faster on Linux than on Windows?

TimP — Sun, 02 Mar 2008 04:10:28 GMT

Shining Arcanine wrote:

I am not quite sure what you mean by "Try running test on native OS in both cases w/o VM."

Run it without a virtual machine. The Ubuntu 6.10 disc can be used as a LiveCD. In this case though, the performance issues seem to be with the host operating system, so if anything running Linux on bare metal would only skew the numbers more.

If you were having problems with the Linux side I would offer my help, but unfortunately I don't have much experience debugging or tuning unmanaged applications on Windows.

Tech Off - Why does my C program run faster on Linux than on Windows?

TimP — Sun, 02 Mar 2008 02:57:28 GMT

Shining Arcanine wrote:

TimP wrote:

So it is indeed doing dynamic linking. Maybe passing shared objects to gcc implicitly tells it to link them dynamically, but I've never seen it done before (I usually see -l).

Since the running time seems to grow with the size of the input, my only guess is that threading is being (ab)used in a way that pthreads handle more gracefully than Windows threading (assuming pthreads-win32 is a wrapper for Windows threads). I would attempt to run to core calculations of the algorithm without any threading involved and compare the numbers.

Those numbers are without any threading involved. The original ones for WIndows were with threading involved.

Is the processor multicore? (I didn't see it mentioned in the OP) If it isn't, threading code is just overhead and performance will be degraded on your Windows test.

Tech Off - Why does my C program run faster on Linux than on Windows?

TimP — Sun, 02 Mar 2008 02:40:47 GMT

So it is indeed doing dynamic linking. Maybe passing shared objects to gcc implicitly tells it to link them dynamically, but I've never seen it done before (I usually see -l).

Since the running time seems to grow with the size of the input, my only guess is that threading is being (ab)used in a way that pthreads handle more gracefully than Windows threading (assuming pthreads-win32 is a wrapper for Windows threads). I would attempt to run to core calculations of the algorithm without any threading involved and compare the numbers. I'm not sure what you're using to do your timing, but there is a time program standard on Linux that you can use that will give you a more detailed breakdown.

time ./a.out

Tech Off - Why does my C program run faster on Linux than on Windows?

TimP — Sun, 02 Mar 2008 02:26:25 GMT

W3bbo wrote:

TimP wrote:
Perhaps gcc is performing optimizations that VC++ is not. Try compiling them both with no optimizations and test the run times. If they're equivalent, then gcc is optimizing more aggressively, otherwise the culprit is elsewhere.

Optimizations are good... but I'd never expect a 50% gain in performance with them.

I would assume so too, but it's worth ruling out.

I'm slightly confused by the invocation of gcc.

gcc -m32 -O2 -fomit-frame-pointer -mtune=k8 -march=k8 mersenne.c /usr/local/lib/gmp.so

Adding the path to gmp.so, in particular. If my understanding of the gcc documentation is accurate, it will regard gmp.so as an "in file", which would seem to imply (if gcc is not complaining) that gmp.so is being statically linked with your executable. You can test this by running ldd yourbinary. If you don't see gmp.so in the output, you're statically linking. I'm not well versed on VC++, so I don't know if your VC++ build is performing static linking or how you would check on Windows. Can anyone chime in?

Back to the point at hand though, if this was the case you should have a fixed delay since dynamic linking resolution is done at invocation and the runtime differences would always be different by a roughly fixed amount.

Tech Off - Why does my C program run faster on Linux than on Windows?

TimP — Sun, 02 Mar 2008 02:16:05 GMT

Perhaps gcc is performing optimizations that VC++ is not. Try compiling them both with no optimizations and test the run times. If they're equivalent, then gcc is optimizing more aggressively, otherwise the culprit is elsewhere.

Tech Off - Profilers

TimP — Mon, 25 Feb 2008 23:13:01 GMT

gprof.

Tech Off - using a Managed DLL from an unmanaged one?

TimP — Tue, 12 Feb 2008 19:36:47 GMT

Have you looked into Managed Extensions for C++ at all? I personally have never used it, but it seems to popular way to tie managed and unmanaged code together. The /clr option still compiles it to MSIL, but I'm not sure exactly what Maya's restrictions are.

Tech Off - C file function questions

TimP — Thu, 31 Jan 2008 00:02:18 GMT

evildictaitor wrote:
Unless you have good reason not to, always use the safe libraries.

I think a good reason is that fopen_s doesn't exist in glibc and is not POSIX compliant. If you're going to lock yourself into VC++ with Microsoft CRT extensions, you might as well be using C#.

Tech Off - Looking for x86 assembly books (with a twist)

TimP — Fri, 25 Jan 2008 06:59:39 GMT

I'm working my way through a computer science degree and despite being exposed to assembly programming, courses tend to focus on RISC architectures like MIPS. While the general ideas of assembly programming are similar across all architectures, the PC market is mostly x86 and I find myself lost in the adx, eax, ebx, movl, etc. soup.

The twist (if you want to call it that) is that I'm not a hardcore assembly nut who thinks that "performance means using assembly" and I avoid assembly programming when I can move up the abstraction chain without significant consequences. However, reading things like Raymond Chen's blog, Understanding the Liunx Kernel, and Windows Internals makes me wish I could follow x86 better.

So with that in mind, I'm looking for a book that explains the x86 assembly language as well as the x86 architecture in general. A list of all the instructions and what they do is not what I'm looking for. I'm curious about the whole architecture from areas such as booting to disk and other device access. I'd also prefer something that's readable as opposed to a link to the Intel or AMD hardware reference manuals. Something reasonably current would be nice. It doesn't have to cover x64 extensions, but I definitely want coverage of i386/32-bit.

Coffeehouse - What was the last fun, free thing you downloaded from MS?

TimP — Thu, 17 Jan 2008 20:35:40 GMT

The PDF export plugin for Office 2007.

Tech Off - Guitar Hero III for PC not playing nicely with power saving on Vista

TimP — Wed, 09 Jan 2008 11:29:41 GMT

I spent some time today sleuthing and it appears that when the guitar controller is unplugged, the system will power down the monitor according to the settings.

This brings up another question. Why does the guitar disable monitor sleep? (my mouse, another USB device, does not) Is there a way to override the setting?

Tech Off - Guitar Hero III for PC not playing nicely with power saving on Vista

TimP — Tue, 08 Jan 2008 02:15:35 GMT

I recently purchased Guitar Hero III for PC and while the game itself is fun and runs fine, the software in general is not very respectful to my settings.

My biggest gripe is that it seemingly disables monitor sleep mode. I have my monitor sleep after five minutes and I can see the importance of disabling that for the duration of the game, but after I exit my monitor doesn't sleep anymore, what's worse is that even after reboots it still doesn't sleep. I checked the power management control panel and all my settings are intact, so GH3 is doing something more sneaky.

A lesser, superficial gripe is that it disables cursor shadows after every exit, but at least I can fix that myself.

To add insult to injury, GH3 complains that its "security software" cannot load and the game terminates if I try to run Sysinternals Process Monitor to see what it's sticking its hands into.

To get back to the primary concern though, does anyone know what the game could be doing to break my power saving settings like this and if there's a way to fix it?

Thanks!

Coffeehouse - What would it take?

TimP — Thu, 13 Dec 2007 04:49:07 GMT

wkempf wrote:

Moreover, a development tool doesn't make much sense as a reason to choose an OS, at least to me.

It's the most common reason I hear among the developer crowd. Microsoft has the game planned out well. Developers refuse to try other platforms because of the perceived absolute supremacy of Visual Studio, said developers develop more Windows applications, users are less likely to switch because said programs will only run on Windows. No wonder they give them away for free.

Tech Off - FSHARP

TimP — Wed, 12 Dec 2007 06:40:25 GMT

CompGuy101 wrote:

What can F# do that I cannot do in VB / C#?

Nothing, it's the ease and clarity of implementation that's different.

Coffeehouse - Why doesn't Microsoft buy SCO?

TimP — Tue, 11 Dec 2007 20:59:51 GMT

The problem is that Microsoft does not emulate the S3 Trio properly. The hardware S3 Trio supports 24-bit color, VPC tells Linux it has an S3 Trio, so Linux assumes it has 24-bit support, and you're blaming this problem on Linux? If you don't or can't emulate a video card properly, just make your own. VMware uses their own SVGA adapter that doesn't exist in any hardware form, yet Linux supports it out of the box.

Coffeehouse - Why doesn't Microsoft buy SCO?

TimP — Mon, 10 Dec 2007 19:59:33 GMT

DigitalDud wrote:

OSX is the only *nix OS that is truly user friendly, by a long shot.

A/UX is pretty user friendly on my Quadra 650. All the coziness of System 7 with SVR3 UNIX underneath.

Coffeehouse - Why doesn't Microsoft buy SCO?

TimP — Sat, 08 Dec 2007 07:24:29 GMT

To follow up, try typing uname -a on your department Unix machine to identify the kernel. While it may look like Unix, I would be genuinely surprised if it was SCO Unix, since I've never heard of any universities running it this decade.

Coffeehouse - Why doesn't Microsoft buy SCO?

TimP — Sat, 08 Dec 2007 07:04:58 GMT

Shining Arcanine wrote:

Perhaps I am going a bit far, but I would really like the ability to buy a copy of Unix for my home PC for $15.75 at my university's store like I can with Windows Vista Ultimate, so I tried to make the best case I could for why Microsoft should buy SCO.

http://www.ubuntu.com/
http://www.freebsd.org/
http://www.openbsd.org/
http://www.sun.com/software/solaris/

Besides, I think that Novell vs. SCO lawsuit determined that SCO never "owned" Unix and that all Unix-related assets belong to Novell.