Slashdot Mirror
Firefox Faster In Wine Than Native
An anonymous reader writes "Tuxradar did some benchmarks comparing Firefox's Windows and Linux JavaScript performance. 'We did some simple JavaScript benchmarks of Firefox 3.0 using Windows and Linux to see how it performed across the platforms — and the results are pretty bleak for Linux.' Later on, they tried Wine. 'The end result: Firefox from Mozilla or from Fedora has almost nil speed difference, and Firefox running on Wine is faster than native Firefox.'"
Check the doco
Firefox 3.0 built for Windows was PGOed (Profile Guided Optimisation)
PGO was not yet enabled for linux builds
Try a newer build.
FAIL
The Singularity is closer than you think
Quant
On the flip side, the pop-unders I get from my local newspaper's site under Firefox don't happen under Linux, only Windows.
"Can't you see that everyone is buying station wagons?"
Seriously, how fast does a web browser *need* to be? I've never been using Firefox on Linux and thought to myself that it was prohibitively or even annoyingly slow.
Reading TFA, in most cases, the differences in times don't seem dramatic, either, so who really cares?
By default Firefox for Linux uses shared system libraries rather than statically linking them altogether as the Windows version does. That's bound to have an impact on performance because code and data pages will be all over the place. Type "about:buildconfig" into the browser and it will tell you its build settings.
Profile Guided Optimization (PGO) is where you compile a special "recording" build of a program, then run it just using your core feature set and "ordinary" tasks. You don't perform a full test, or click on all the options or settings, you just go through normal end-user use cases. The special build then records a "profile" of your typical usage. You then feed the source code plus the profile back into the build process to build your production code.
The idea is for the linker to identify the hot spots in memory, and group as many of them together as possible so they live on common pages. This helps keep those pages from being swapped out of memory to disk due to disuse, which greatly reduces the amount of thrashing your end users will see during normal use. Less thrashing == improved performance.
John
Oops, sorry, I didn't answer your "why not?" question directly. My guess is that because it takes a fair amount of additional work to create the profile after each build, the step may have been skipped by the Linux build team. As far as I know, profiles are unique to each build: you can't create a profile under the Windows image and reuse it on the Mac or Linux builds.
That's just a guess, though, I could certainly be wrong about that. I'm sure a PGO expert or perhaps a member of the Firefox build team will chime in here soon to correct me if I am.
John
That's way off base. There are no context switches when making a library call. Context switches occur when you ask the kernel to do something by making a syscall. So memcpy or memcmp don't incur a context switch. Nor do fopen or fread in and of themselves cause context switches. But one will occur when the underlying open and read calls are made.
What's really needed here is a profiler to find where the code is spending the bulk of its time. My guess is that it's a compiler issue. And other comments about the windows build using profile guided optimization tell me my guess is probably right.
You obviously have no idea what a context switch is.
A context switch happens when the scheduler stops one process/thread and gives the CPU to a different one. This has nothing to do with cross-library calls.
sig intentionally left blank
PGO in GCC: http://gcc.gnu.org/install/build.html#TOC4
Colorless green Cthulhu waits dreaming furiously.
It doesn't really have to do with X or Firefox so much as the interaction between X and Firefox. Composition effects and pixmap caching at the two prime issues.
Composition is when you draw an image that blends with what is already on the screen. Right now, a lot of the Xorg code that accelerates composited effects is unfinished. In particular, rendering composited text is painful. The brute force solution of blending with what is on-screen is awful, because reading from video ram is very, very expensive. So optimizing this is pretty non-trivial since the optimization must be that you don't look at what you need to blend with! Progress is happening though.
Pixmaps are used to store images in the X server. Firefox, to get the rendering effects it wants, often uses large pixmaps for application elements. Large pixmaps can cause memory fragmentation issues, making later allocations harder, causing performance to slowly decline over time. Again, this is something being worked on, but in this case, the client is really not behaving very nicely.
Like I said, progress is being made on these fronts - Xorg's xserver 1.5 and 1.6 are supposed to have some good acceleration improvements. There's been work on a much improved glyph cache for EXA accelerated fonts. I haven't run any of these, since my distro currently ships 1.4, and I don't really plan on upgrading until Debian does. But since it's a pain point for me, and I read the development mailing list, I thought I'd share.
Browser response, not speed, is what annoys most people on Firefox, since version 1.
Instead, it's the lack of threading - that the notion "UI, the rending engine, and plugins should run in separate threads, with the UI thread having the highest priority".
Konqueror runs Flash player in its own process "nspluginviewer", which I can renice to 19 - just like how IE runs Flash in the lowest priority by default. Still, on Firefox 3, a few tabs running CPU-intensive Flash can still effectively freeze the browser UI.
The profile in question here is a profile of what variables and chunks of code the program (in this case FireFox) uses the most, not your FireFox user profile. By knowing this it knows stuff like what variables are read and or written the most and the least and it knows what functions should be next to other functions used at the same time. This gives it a good idea of where to store things when it compiles the source. For example the variable containing the users bookmarks will not get accessed as frequently as variable containing the current tabs. While this profile could be effected by how the user uses FireFox it is very unlikely to be a significant difference.
I think that is why GP said the impact of swapping "for an average desktop linux user is almost non-existent" ...because for an average desktop linux user swapping is almost non-existent.
I've run Linux machines (for short periods of time, with no more than normal desktop use loads) without any swap, and they work fine... but when you hit that wall of running out of physical RAM you'll feel it a lot more without swap than you would with a swap file/partition.
Windows on the other hand seems to want to use several hundred megs of swap whether it needs it or not.
I am not sure how you got modded insightful. Linux, in terms of the kernel, is in fact a monolithic structure but has nothing to do with the API/lib/small packages that can be chained together that the OP was talking about. Linux in the GNU/Linux sense (a distribution), is in fact composed from many small libraries that each perform a specific function well.
Regarding your point about how the app was built: How do you draw a distinction between the Windows, Linux, and UNIX builds of Firefox? I'll help you - each version is a port using libraries on the system that it is ported to. Those dependencies do in fact have an impact on compilation, how the memory map is built, and how well the application performs.
Also - the optimization process differences are significantly more complicated than you implied. I strongly suspect, although am not positive because I have never built it from source or examined how an RPM was built, that the Linux Firefox build was done with at least -O2 or -O3 flags. The difference that FP was talking about was PGO (Profile Guided Optimization), which is more involved (and thus better performance gains) than just turning on the default compiler optimizations.
Actually he's right but in the wrong direction. On Wine many things that would be pure syscalls on Windows do force a context switch into the wineserver, because the emulated "kernel" is actuall a separate process. For instance opening a file involves an RPC to the wineserver on Wine, whereas it simply switches into kernel mode on Windows and there's no TLB flush overhead. The fact that Firefox is still faster under Wine than native suggests a serious bottleneck somewhere rather than a general problem - if I had to choose, I'd pick text rendering as my first guess.
Firefox appears to be using an inefficient method to render the content to the screen. If a load up a page in Firefox and drag the window around fast, the content inside the window tears and blurs and stays that way for a second after I stop whipping the window around. Konqueror and Opera don't do this.