Thanks for the clarifications. I was trying to evaluate if was worth writing my own shared memory module for my particular use-case. (obviously for dynamic Bitmap sizes, using the Binder mechanism will lead to the issues you point out).
On May 26, 5:33 pm, Dianne Hackborn <[email protected]> wrote: > Like I said, it is part of a much lower-level part of the IPC system, so > independent of what you are doing at the level of marshalling a bitmap > across processes. I don't have the exact number off-hand, but if you are > thinking about this as a limit on how big a bitmap you can send, you are > probably going to have other problems (such as multiple local allocations to > hold the data and the copying overhead) before that comes into play. As a > rule I would avoid sending anything more than 100K across processes, and > really try to keep that far less... and though the current impl does allow > for far more, as I said other performance issues will come into play and > that memory is used for all active transactions delivering data or replies > to the process. > > Also, this memory is not shared between two processes, it is shared between > the kernel and the process it is delivering data to. > > > > On Tue, May 26, 2009 at 5:22 PM, George <[email protected]> wrote: > > > Thanks Dianne. > > > Is the shared memory size fixed? If yes, what is typically the size? > > > On May 26, 4:59 pm, Dianne Hackborn <[email protected]> wrote: > > > Depends on how you define this. It makes a copy of the bitmap. The > > > underlying Binder IPC mechanism uses shared memory to deliver data, but > > this > > > isn't happening up at the Bitmap level so you have at least a couple > > copies > > > of the data being made. > > > > In general, please avoid sending anything except icon size bitmaps across > > > processes. > > > > On Tue, May 26, 2009 at 4:49 PM, George <[email protected]> wrote: > > > > > When I pass a Bitmap using the Binder Remote service mechanism, does > > > > the internal implementation of writeToParcel/createFromParcel of the > > > > Bitmap class use shared memory? > > > > -- > > > Dianne Hackborn > > > Android framework engineer > > > [email protected] > > > > Note: please don't send private questions to me, as I don't have time to > > > provide private support, and so won't reply to such e-mails. All such > > > questions should be posted on public forums, where I and others can see > > and > > > answer them. > > -- > Dianne Hackborn > Android framework engineer > [email protected] > > Note: please don't send private questions to me, as I don't have time to > provide private support, and so won't reply to such e-mails. All such > questions should be posted on public forums, where I and others can see and > answer them. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -~----------~----~----~----~------~----~------~--~---
