Stephen John Smoogen wrote: > On Nov 7, 2007 7:09 PM, Albert Cahalan <[EMAIL PROTECTED]> wrote: > >> On 11/7/07, Michael Stone <[EMAIL PROTECTED]> wrote: >> >>> On Wed, Nov 07, 2007 at 12:06:21PM -0500, Albert Cahalan wrote: >>> >>>> Next, bind-mount something appropriate onto /tmp and /var/tmp. >>>> >>> I talked about this with Ivan who requested, at the time, that we >>> continue using the $SAR directories instead of the FHS ones. >>> >>> The basic idea was that we actually _do not_ want activities scribbling >>> all over the filesystem. Period. Certainly we could use the standard >>> paths, as you suggest. However, it was an intentional design decision to >>> break compatibility with the FHS. >>> >> Using standard directories is not scribbling all over >> the filesystem! >> >> This anti-compatibility attitude needs to stop. It's really >> hurting OLPC, needlessly making the goals harder to >> achieve. Breaking compatibility is something to be done >> as a last resort, when no alterative will work. >> >> The long-term goal should be to support solid sandboxing >> of true all-over-the-filesystem software installs. This may >> need a unionfs filesystem so that files can be put everywhere >> without the dummy files needed for file-on-file bind mounts. >> Imagine if you could install any RPM, knowing that it had >> no way to corrupt your OS. >> >> > > A couple of questions from someone who is trying to catchup on what he > might be able to do > > 1) How much indirection can the CPU handle via various layers (say > unionfs ontop of unionfs etc) without bogging down the system? >
That would be a difficult question to answer without a lot of handwaving. That said, the bottleneck is likely to be the compression/decompression in the JFFS2 driver. To the extent that you can avoid stuff ever hitting the NAND FLASH, you probably win. > 2) How much can the flash drive handle per throughput AND lifetime limits? > Throughput is dominated by compression / decompression. The latter goes at about 3 MB/sec; the former is probably slower. Lifetime is not likely to be a problem. JFFS2 is good at spreading out writes. > 3) How much can the memory system handle? since... I don't think we > want to hit swap. > Especially since there is no swap. > If all these are generally known and been discussed already.. sorry. > > _______________________________________________ Sugar mailing list [email protected] http://lists.laptop.org/listinfo/sugar
