More Context on Memory Reservation Issues on PS3
I wrote earlier about some of the improvements the 1.6 firmware update was supposedly going to bring to the PS3. At the time, one of the things that struck me as odd was just how much memory some of the new online features (such as the Friends list and online store in game) took up compared to what we had done with the 360. I wanted to try and compare and contrast in more detail, but couldn't remember what we had announced publicly, especially around our memory reservation. So I pinged Pete Isensee here at Microsoft and asked him what we might be able to share externally. Pete manages the XNA Developer Connection and knows exactly what we've said, when, and to who. (I wish I had his memory. )
Anyway, in classic hurried Microsoft fashion, I only sent quick bulleted questions; Pete returned his usual thoughtful responses from those. With thanks to Pete, I just wanted to share some context with you on why the PS3's memory reservation numbers are so bad, and the implication that has on future games.
Can you remind me what CPU/Memory reservation we have on the 360 – and is this public? I think 32MB is memory, don’t remember CPU.
Xbox 360 reserves 32 MB for the system. The remaining 480 MB (94%) is completely available for games to use how they wish. The 32MB of system memory is used for the kernel, device drivers and the Xbox 360 Guide, which includes friends lists, voice/text messages, achievement lists, gamercards, Live Marketplace, 1-1 chat, virtual keyboard, and the music player. For CPU reservation, core 0 is completely available to the game, and the system reserves a small percentage (think single digits) of core 1 and 2.
If those are true, Sony’s rumored numbers seem insanely huge – am I missing something here that can help justify?
Sony’s numbers are massive in comparison. The Xbox team knew from day one of Xbox 360 system development that we needed to accomplish two things: 1) let game developers focus on writing their game, and 2) give game developers plenty of memory to make great games. A ton of work has gone into making sure the OS is as tiny as possible. Our best engineers have focused on ensuring the components that make Xbox 360 so easy to use – like unified friends lists, custom music in every game, a legally-compliant global commerce system (Live Marketplace) – all fit within 32MB, with enough space left over so we can expand features in the future without affecting any existing games. The unsung heroes of Xbox 360 are the engineers who’ve constantly tuned the memory footprint of the system.
For comparison, PS3 developers have to deal with a system that has memory split into two 256MB banks, one of which is reserved for graphics only. A large portion of both the memory banks are reserved for the system. On top of that, games that want to support other features, like friends lists or in-game commerce, take an additional memory hit. http://arstechnica.com/news.ars/post/20060413-6600.html indicates that a total of 96MB is reserved for the system on PS3. http://www.innerbits.com/blog/2007/02/27/ps3-online-background-downloading-the-sony-way/ indicates that 9MB is required for friends lists (and 60MB for in-game commerce!). If those numbers are correct, a PS3 title using friends lists functionality has 512-96-9 = 407MB available, 73MB less than an Xbox 360 title using the same features.
If Sony mandates these features in future titles (unlikely for in-game Commerce, possible for friends), game developers will cut other game features to meet a smaller memory footprint. If Sony doesn’t mandate these features, then games won’t universally support them. Either way, gamers lose.
What do we have “in” the Guide (already reserved) vs. what a developer would need to allocate more memory for? Thinking in-game shopping experience in particular – are we all covered in the 32 MB?
The Xbox 360 Guide already supports the Marketplace experience, so in most cases an Xbox 360 game doesn’t need to allocate any additional memory. If the title wanted to have an in-game experience, they’d just need to carve out a small chunk to manage in-game images, descriptions and prices. Games on Xbox 360 still call into Marketplace to make the final purchase, but that’s a good thing, given that no game developer or publisher is much interested in dealing with all the ramifications (legal, engineering, policy, technical requirements) of transacting purchases within a game itself.
Fuente:
http://ozymandias.com/
LINK:
http://ozymandias.com/archive/2007/03/22/More-Context-on-Memory-Reservation-Issues-on-PS3.aspx
- Resumiendo:
X360: 512-32= 480 MB RAM avaiable
PS3: 512-96-9 = 407MB RAM available
Ram disponible para los programadores de juegos, restamos la correspondiente al Sistema Operativo.
Estos ingenieros de Sony...Tanta RAM para tan poco S.O.
Un chiquipunto para Sony!
