"Maybe I'm just naive, but designing a graphics API such that all image data had to be sent over a socket to another process every time the image needed to be drawn seems like complete idiocy. Unfortunately, that is precisely what the X Window System forces a program to do, and exactly what Cairo does when drawing images in Linux - a full copy of the image data, send to another process, no less, every time it is drawn. One would think there would be some room for improvement. Unsurprisingly, others felt the same way about X, and decided to write an extension, Xlib Shm or XShm for short, that allows images to placed in a shared memory segment from which the X server reads which allows the program to avoid the memory copy. GTK already makes use of the XShm extension, and it seems like a good idea to see if Gecko couldn't do the same."
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Member since:2005-07-06
Fedora 9 with all updates, redeon driver, AMD 3870, Phenom 9750
[storm@fast ~]$ x11perf -putimage500
x11perf - X11 performance program, version 1.5
The X.Org Foundation server version 10499902 on :0.0
from fast
Sun Jun 29 14:11:16 2008
Sync time adjustment is 0.0334 msecs.
2800 reps @ 2.0214 msec ( 495.0/sec): PutImage 500x500 square
2800 reps @ 1.9846 msec ( 504.0/sec): PutImage 500x500 square
2800 reps @ 1.9471 msec ( 514.0/sec): PutImage 500x500 square
2800 reps @ 1.9314 msec ( 518.0/sec): PutImage 500x500 square
2800 reps @ 1.9462 msec ( 514.0/sec): PutImage 500x500 square
14000 trep @ 1.9661 msec ( 509.0/sec): PutImage 500x500 square
[storm@fast ~]$ x11perf -shmput500
x11perf - X11 performance program, version 1.5
The X.Org Foundation server version 10499902 on :0.0
from fast
Sun Jun 29 14:12:17 2008
Sync time adjustment is 0.0305 msecs.
16000 reps @ 0.3851 msec ( 2600.0/sec): ShmPutImage 500x500 square
16000 reps @ 0.3684 msec ( 2710.0/sec): ShmPutImage 500x500 square
16000 reps @ 0.3661 msec ( 2730.0/sec): ShmPutImage 500x500 square
16000 reps @ 0.3684 msec ( 2710.0/sec): ShmPutImage 500x500 square
16000 reps @ 0.3680 msec ( 2720.0/sec): ShmPutImage 500x500 square
80000 trep @ 0.3712 msec ( 2690.0/sec): ShmPutImage 500x500 square
~5 times faster, not bad.
Member since:2007-09-08
openSUSE 10.3, Intel Q6600, Nvidia8600 GTS nvidia binary drivers, 2560x1600 resolution, 32 bpp
x11perf -putimage500
x11perf - X11 performance program, version 1.5
The X.Org Foundation server version 70200000 on :0.0
from monsta
Sun Jun 29 14:38:21 2008
Sync time adjustment is 0.0413 msecs.
8000 reps @ 0.7415 msec ( 1350.0/sec): PutImage 500x500 square
8000 reps @ 0.8194 msec ( 1220.0/sec): PutImage 500x500 square
8000 reps @ 0.9253 msec ( 1080.0/sec): PutImage 500x500 square
8000 reps @ 0.8722 msec ( 1150.0/sec): PutImage 500x500 square
8000 reps @ 0.8803 msec ( 1140.0/sec): PutImage 500x500 square
40000 trep @ 0.8477 msec ( 1180.0/sec): PutImage 500x500 square
x11perf -shmput500
x11perf - X11 performance program, version 1.5
The X.Org Foundation server version 70200000 on :0.0
from monsta
Sun Jun 29 14:39:16 2008
Sync time adjustment is 0.0385 msecs.
12000 reps @ 0.4442 msec ( 2250.0/sec): ShmPutImage 500x500 square
12000 reps @ 0.4435 msec ( 2250.0/sec): ShmPutImage 500x500 square
12000 reps @ 0.4433 msec ( 2260.0/sec): ShmPutImage 500x500 square
12000 reps @ 0.4429 msec ( 2260.0/sec): ShmPutImage 500x500 square
12000 reps @ 0.4424 msec ( 2260.0/sec): ShmPutImage 500x500 square
60000 trep @ 0.4433 msec ( 2260.0/sec): ShmPutImage 500x500 square
Only two times faster. Or in other words, already the core X on a local server is very fast and does not use TCP/IP when local.
Don't get me wrong, I use MIT-SHM for 14 years in my programs. But in optimization, you need to look at the total cost, not just optimize because you can. The actual time spent in copying the image buffer is most likely negligent with respect to generating the image data. So you will get better overall speedup by optimizing other part of the application.
In the old times, this data transfer was very slow, so optimizing it by MIT-SHM make a lot of sense. Nowadays, graphics cards are very fast (even on high resolutions like the ones I use), so optimizing with MIT-SHM does not buy you much (in the total application speed).
"Ilja van Sprundel, a security researcher with IOActive, has discovered a large number of issues in the way various X client libraries handle the responses they receive from servers, and has worked with X.Org's security team to analyze, confirm, and fix these issues."
"Google is facing a new antitrust probe by the U.S. Federal Trade Commission into whether the company is using its leadership in the online display-advertising market to illegally curb competition, people familiar with the matter said." Sucks to be Google today, apparently.
"In the midst of the major press blitz surrounding its annual I/O Conference, Google dropped some unfortunate news about its instant messaging plans. In several places around the web, the company is replacing the existing 'Talk' platform with a new one called 'Hangouts' that sharply diminishes support for the open messaging protocol known as XMPP (or sometimes informally Jabber), and also removes the option to disable the archiving of all chat communications. These changes represent a switch from open protocols to proprietary ones, and a clear step backward for many users." That's why I always say: only suckers trust companies.
"The wave of departures is a sign of internal struggle, but amidst all the bad news, there is a glimmer of hope. According to an anonymous HTC executive cited by WSJ, the crucial HTC One is selling 'pretty good so far'. The executive revealed that HTC sold about five million One units since launch, a performance that is deemed encouraging. However, sales have been limited by the persisting supply issues that still plague the production of the HTC One." Finally some good news for HTC. Five million units amidst supply constraints is very impressive.
"Sony gave the PS4 50% more raw shader performance, plain and simple (768 SPs @ 800MHz vs. 1152 SPs & 800MHz). Unlike last generation, you don't need to be some sort of Jedi to extract the PS4's potential here. The Xbox One and PS4 architectures are quite similar, Sony just has more hardware under the hood. Weâll have to wait and see how this hardware delta gets exposed in games over time, but the gap is definitely there. The funny thing about game consoles is that itâs usually the lowest common denominator that determines the bulk of the experience across all platforms. On the plus side, the Xbox One should enjoy better power/thermal characteristics compared to the PlayStation 4. Even compared to the Xbox 360 we should see improvement in many use cases thanks to modern power management techniques." AnandTech does its usual in-depth thing."The Verge has learned that HTC's Chief Product Officer, Kouji Kodera, left the company last week. Kodera was responsible for HTC's overall product strategy, which makes the departure especially notable on the heels of the global launch of the make-or-break One. It's not just Kodera. In the past three-odd months, HTC has lost a number of employees in rapid succession." I really hope HTC pulls it together.
"It is with huge pleasure that the Debian GNU/Hurd team announces the release of Debian GNU/Hurd 2013. This is a snapshot of Debian 'sid' at the time of the Debian 'wheezy' release (May 2013), so it is mostly based on the same sources. It is not an official Debian release, but it is an official Debian GNU/Hurd port release." Important note: 75% of Debian packages are supported bu Debian GNU/Hurd. Impressive.
"The first killer app was VisiCalc. This early spreadsheet turned the Apple II from a hobbyist toy to a business computer. VisiCalc came with room for improvement, though. In addition, a new architecture and operating system, the Intel-based IBM PC and MS-DOS, also needed a spreadsheet to be taken seriously. That spreadsheet, released in early 1983, would be Lotus 1-2-3, and it would change the world. It became the PC's killer app, and the world would never be the same. On May 14, IBM quietly announced the end of the road for 1-2-3, along with Lotus Organizer and the Lotus SmartSuite office suite. Lotus 1-2-3's day is done." Impressive 30 year run."There's a disconnect between how Apple CEO Tim Cook sees his company's tax strategies and how some members of the US Senate view it. That became clearer than ever today after Cook and two other Apple executives testified before Congress, explaining why they're holding most of their international income in Irish subsidiaries like Apple Operations International, which declare no tax residency anywhere in the world. AOI hasn't filed a tax return anywhere in the world for the last five years, yet it earned $30 billion in income from 2009 to 2012, according to a Senate report released yesterday." Just because something is legal, doesn't mean it's just. Apple, Google, Microsoft, and many more - these companies might not be breaking any laws, but it's obvious to anyone that what they are doing is scummy.
The new WebKit Opera for Android has been released. "Opera 14 for Android is built on top of Chromium 26, with a total overhaul of the UI in native code, making it fit well with the latest Android design guidelines. Go get the build from Google Play or point your browser to m.opera.com, and give it a spin!"
Member since:
2005-11-20
Well, we are speaking about Cairo here right?
Cairo is basically a software renderer. That implies that in fact you do all your rendering to the memory, then transfer the resulting image to X11.
That in fact implies that you rarely are able to "reuse" stored images. Each screen update means a new image and new transfer.
IME, the difference in image transfer is about 2x. OTOH, the rendering itself can perhaps take quite a bit of time too, so in practice, maybe it really is not that critical.
BTW, you can try it:
x11perf -putimage500
x11perf -shmput500