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Gzip on a PCI card
steve writes "The German tech news site heise.de is reporting here (in German, of course) about a PCI card developed by the Universiy of Wuppertal and Vigos AG being shown at CeBIT, which does Gzip compression in hardware, thus freeing the CPU to do other tasks. The PCI card can compress 32MB/sec, which is more than enough to compress a 100Mbit LAN in realtime. A future version will do 64MB/sec. The article mentions that this will be of particular interest for web servers. The card should be on sale by the end of the year."
Seems this would be a great help to those doing backups over a LAN. Shouldn't take too much to alter a version of tar , rsync, etc. to use this card.
the key to using gzip is really not to compress at too high a ratio... a low rate of compression offers a pretty sizeable saving in bandwidth for an acceptable CPU usage... once you edge up to the higher compression levels then you pay for it in the CPU and your app slows.
i love the idea of a hardware based gzip... but i'd start by educating the software users on the cost vs benefit ratio of their existing configuration... i always seem to find that those who don't know what they're doing are the ones that have it set to maximum compression
I try to avoid bzip2 because it is so slow, even on modern hardware. bzip2 compresses very well, much better than gzip. A bzip2 version of this card makes sense ....
RFC1925
A translation: A joint venture between the University of Wuppertal and Vigos AG showcase the prototype of a "GZIP accelerator board" at CeBIT (Hall 11, D26). The PCI card removes the burden of performing time-consuming data compression tasks from the system CPU and already achieves a data throughput of 32 MB/s in its current development state. This is sufficient to compress the traffic generated by a 100 MBit LAN connection in real-time; through the modular design, it will be possible to reach 64 MB/s in the future. [end of first paragraph] Specialist
A hardware that does the dirty processing job while freeing the CPU ? Wow, that's new. I'm going to the USPTO to get my patent on this.
Maybe I can even make some money on Intel, as they were in clear violation of my patent with their arithmetic coprocessor for use with the 80386SX family of microprocessors .
For comparison i ran gzip on two machines I happen to have immediate access to, I compressed a 32mb file gotten from /dev/urandom,which probably would be a worst case scenario for a compressor
dd if=/dev/urandom of=32m bs=1024k count=32 ; time gzip 32m
P4-1.8Ghz:
real 0m4.428s
user 0m4.220s
sys 0m0.170s
AthlonXP2200+
real 0m3.579s
user 0m3.310s
sys 0m0.160s
So 32MB/s sounds pretty good to me.
Thoughts on tech, Software Engineering, and stuff
Most all current browsers will automatically uncompress gzipped files sent to it, allowing things such as the mod_gzip module to compress web pages and have them rendered on the browser transparently. The bandwith savings ccan be huge, with all the associated benefits (less bandwith for the server, less for the clients and less congestion on the net). Without bzip2 support built into the browser, the hardware compression isn't useful for general web traffic, as it can't be used for the pages being sent.
It'd be nice if I could convince my boss to get some of these for us, but our CPU usage is pretty low right now with the mod_gzip module installed, so it'd be an unnecessary luxury at this point for us.
I am, and always will be, an idiot. Karma: Coma (mostly effected by
The general trend in the industry goes to non-intelligent interconnections (Gigabit card used to have a processor (Alteon), they don't anymore (see latest intels)). I2O never took off because you don't really need to relieve a computer from computation when your computation power is pletoric.
On a Xeon 2.8GHz, I just got 71 MB/s for gzip.
What's the use for such hardware then?
Plus it will eat the PCI bus because data has to go out of memory to processing card, back to memory, then to network card. You triple the PCI bus bandwidth. (Not true if the compression is embedded in the network card).
The best idea would be to make the chip an FPGA not a specially-designed processor. Then you could load in different chip designs for whatever was currently needed. Need to do RSA encryption? The board reconfigures the FPGA for it. Same goes for Divx compression, gzip, SETI@Home, etc. FPGAs take a few milliseconds to reconfigure but when they operate as a dedicated signal processor they can leave a general purpose processor in the dust - leaving the main CPU to run the other apps, the desktop, etc.
Check out the IEEE archives and journals, searching for "adaptive computing" or "reconfigurable computing".
KingPrad
Stop the Slashdot Effect! Don't read the articles!
Good point ... lets test a little more:
P4-18Ghz: gzip -9
real 0m4.437s
user 0m4.200s
sys 0m0.210s
P4-18Ghz: gzip -1
real 0m4.366s
user 0m4.130s
sys 0m0.200s
AthlonXP2200+: gzip -9
real 0m3.387s
user 0m3.160s
sys 0m0.210s
AthlonXP2200+: gzip -1
real 0m3.427s
user 0m3.200s
sys 0m0.170s
The really funny part is that I ran the Athlon one several times and the gzip -9 was always just ever so slightly faster than the gzip -1 version.
Maybe random data is not the best for testing the different compression levels though, since if it is truly random it cannot be compressed no matter how hard you try.
Even if this is not a perfect(or even reasonable) "apples to apples" comparison, it is a good end-to-end system level comparison. While it may not be "4x faster than a 2Ghz CPU", when building a system that _needs_ to do compression, adding this card would _effectively_ boost my CPU speed.
Thoughts on tech, Software Engineering, and stuff
Another thing about gzip is that it is assymmetric: decompression is much faster than compression. Again this is a nice feature, because most files will be decompressed many times but compressed only once. Thus for instance, all man pages are stored in gzipped form and decompressed on demand.
But I can't see the point of implementing it in a PCI card. Wouldn't it be better to integrate it with either the processor or the network interface?
The article mentions that this will be of particular interest for web servers.
I'm assuming one is referring to something that will work with mod_gzip. That may be fine and dandy, but I just recently had to disable mod_gzip on my server. You can blame Microsoft.[1] It seems that both IE 5.5 and 6.0 have nasty little "sometimes" bugs[2] where they won't know what do with gzipped content. I tried to disable by user agent header with no luck. If anyone else has some good pointers or perhaps even a link to a patched version of mod_gzip that'll avoid those two bugs, I would apprieciate it.
[1] No, really. This isn't a troll. They even admit the bugs.
[2] Microsoft Knowledge Base Articles: Q313712 IE 5.5 Q312496 IE 6.0
When the PCI bus is taken, other stuff that the CPU needs to do will also be halted. And then the PCI bus is much slower than the FSB.
I think what we need to push distributed computing more is altering the RAM and DMA channels. There should be many physical channels to the RAM capable of simultaneously reading/writing different parts of it. As in if the ram can output 200 MB per sec, 16 devices could attach themselves to the RAM via maybe EDMA (enhanced DMA?) and simultaneously be able to read at 200MB each. This might be done by:
(1) Altering the addressing logic in the memory ICs, maybe put 16 different addressing systems and multiply their pins x16. Then have an external matrix, more advanced than the 802x DMA chip to allow simultaniety.
(2) Seperate the addressing schemes of each chip, so an OS kernel could smartly put data of important processes in the right chip to be worked on by external devices.. again also having an external matrix for the address multiplexing.
This way such a PCI gzip device could have its PCI address space, IRQ as well as (EDMA?) address which it would use to access the data to gzip and put back into the RAM, at full speed, not taking up RAM bandwidth, PCI bandwidth, IRQs or the CPU at all.
The AGP as achieved this by seperating the AGP channel from PCI, but still using dedicated memory rather than smartly-shared memory. I understand multiprocessor systems technically do the same thing, but in this case we are treating the external devices like complete slaves, like the GPU, for only dedicated purposes, and I'm emphasizing the smart sharing of memory that doesnt exist in multiprocessor systems either. In this scheme, one could add CPU cards, maybe hot-plugged, and have insta-multiprocessor system or use it to offload kernel compilation, zipping, 3d transformations, or even take user tasks while the main CPU just works in supervisor mode.
"Give orange me give eat orange me eat orange give me eat orange give me you." -Nim Chimpsky
I think it's a little naive to say "Oh, my 1000 hit a day web box, running on a cheap 686 wouldn't benfit from this, so it must suck." Hey, dont get mad! You said it! :P
We at Indra Networks developed a PCI based gzip accelerator a long time ago. It has been on sale for almost a year. The current version of the card is already at 50 MB/s and we have been shipping that since last September. A higher performance version is on the way.
The card is being sold on an OEM basis to manufacturers of load balancers and SSL accelerators. These boxes front-end multiple Web servers and have very high performance requirements. Also, the CPU has plenty of other work to do, for example TCP/IP processing. This is the application that needs hardware acceleration.
For a low performance site, mod_gzip is fine. But, if you have a busy site with hundreds of Web servers, you don't want to go around installing mod_gzip hundreds of times. It is a lot cheaper to buy a load balancer with gzip hardware acceleration.
bzip2 is irrelevant here as IE and Netscape would not understand bzip2 encoding anyway. But they understand gzip just fine (unless you have a version that is many years old).
Monish Shah
CTO, Indra Networks
www.indranetworks.com
A lot of computing records over the years have been set vector computers or other specialized hardware. Putting that power on a PCI-card like this gzip-solution and in addition making the algorithm reprogrammable and reconfigurable you get: Mitron Co-processor on a PCI-card.
has been traditional areas for these kinds of devices, but with the new FPGA's and PCI-express on the horizon I can see it becoming usable for even more specialized applications.
Here is a crude translation of an article in Swedish ( Source Elektroniktidningen)
FPGA enhances PC
You don't have to be a logic constructor to make use of FPGA-chips. Using a normal PCI-card and a compiler from the innovation startup Flow Computing in Lund, programming in Flow's dialect of C is enough.
- We can make a normal PC do calculations that otherwize would have needed supercomputers of large Linux-clusters, said Josef Macznik on Carlstedt Research & Technology, a company that invested and works together with Flow Computing.
The main idea is parallelism. That implies that the PC hardware has to be added in some way, since normal PC-processors works sequentially and normal programs are written to be executed in that way.
Flow has chosen to use normal PCI-cards. The cards are equipped with an FPGA-chip from Xilinx with two million gates, but the size of the chip can be selected depending on requirements according to Josef Masznik.
The corporate secret lies in the compiler. Software has to be written in Flows own variety of C, and the compiler can decide which processes that wins the most on parallell execution, configuring the FPGA for maximum efficiency.
- The user don't see the FPGA-chip and don't really have to know what kind of hardware there is on the card. We are directed towards programmers - that's where the market is, said Josef Macznik.
Flows solution is currently used by a bioinformationcompany in Lund. But the technology can according to the company be used for all purposes where the computing power in a PC needs to be multiplied using parallelism ane where the effort to adapt their programs to the special variety of C is worthwhile.